There's a lot here, so I'll just dive right into it, in no particular order.

ISSUE 1 - Constantly reminded after each mission to spend XP on pilots whose skills can be progressed.
SUGGESTION - Add an option to remove this. We don't need constant reminders, and there are better ways to convey this like unique badges in the Barracks on pilots who have enough XP to gain skills.

ISSUE 2- Binding keys to slots rather than the ability is inconsistent to the user.
SUGGESTION - Allow for binding keys to specific skills, not slots. If I associate Z to SENSOR LOCK, but instead Z is ABILITY 5, which can be SENSOR LOCK for 1 pilot but BULWARK for another. Allowing the player to associate that Z will always be SENSOR LOCK can be more logical.

ISSUE 3 - Inability to bind key to FIRE function.
SUGGESTION - A good UI reduces 2 major loads: Physical (moving hand, mouse, pressing buttons/clicking) and Mental (making me think) If I could bind FIRE to SPACEBAR (or any other key), then I don't have to move my mouse to the button and press click (2 additional loads), I can just press SPACEBAR.

ISSUE 4 - When attempting to bring an enemy within sensor range for locking, UI is prohibitive in simply showing this.
SUGGESTION - If you allow us to right click the enemy in question to bring up the UI that shows their information (this needs to be allowed for out-of range/soon-to-be-in-range enemies), when the camera is fixed on where you can move to get the enemy in range, you are not able to see the outer sensor ring, leading to opportunities where moving resulted in you just missing bringing the enemy within range. If they could look at the UI and see an icon appear that indicated that at that spot to move to, the target IS in sensor range, this would prevent that issue.

ISSUE 5 - No easy way for collectors to know how many Mechs and Variants they have for each Chassis
SUGGESTION - Add UI that allows the player to easily see/sort/filter which Mechs they have and which variants they are missing (and indicators how far they are to building them)

ISSUE 6 - When selecting Salvage, there's no way to know how many Mechs of that Chassis/Variant you already have, leading towards collectors accidentally obtaining chassis they already have Mechs in.
SUGGESTION - Provide this information in context on the Salvage screen. If I'm Looking at CTF-1X salvage, and it says I have 1/3 parts, add how many full Mechs I have of this chassis/variant.

ISSUE 7 - Verbiage issue, but after negotiating a contract, on the load screen, the agreed upon Fee and Salvage rights are erroneously listed as "Max"
SUGGESTION - Change to something like "Negotiated ______" because due to bonuses you can go over these amounts, thus, they are not "Max".

ISSUE 8 - Called shot interface does not provide same tactical data as UI at top center.
SUGESTION - Rather than having the user move cursor between these 2 similar UI elements, provide the weapon location information that the top center UI does in the Called Shot UI, so I can mouse over a part, know how much armor and what weapons are there without having to move between both UI repeatedly to get that information.

ISSUE 9 - Cannot move Mechs around between Bays.
SUGGESTION - Allow the user to drag Mechs between Bays and Slots freely for personal organization needs.

ISSUE 10 - Store list can sometimes be initially displayed halfway down the list.
SUGGESTION - This is a bug and needs to be resolved, otherwise if the user doesn't scroll up, they may miss out on some items they want to purchase.

ISSUE 11 - Contracts show only 1 side's faction and reputation.
SUGGESTION - If you are playing to not take contracts against certain factions, the contract system does not indicate the opposing faction or your reputation with it. This would be helpful information.

ISSUE 12 - Cinematics are inconsistent in which can be skipped
SUGGESTION - Allow the user to skip all cinematics. For example, you can skip the cinmatic of mooring with a Jumpship, but not when you undock from it. All cinematics in and out of game should be skippable. Also, the intro cinmatic is notorious for presenting 'Press ESC to skip', for 2 seconds or so where it does not accept keyboard input.

ISSUE 13 - Allow the RMB to serve dual functionality as Escape.
SUGGESTION - LMB often is used to confirm actions, and allowing the user to click the RMB is faster than the hand leaving home row and pressing ESC for the same functionality.

ISSUE 14 - Sometimes navigating elevated terrain is taken accidentally if user doesn't alter camera angle.
SUGGESTION - When moving, a series of same-size dots appear. Would it be possible to scale those circles larged to indicate the user is rising in elevation? This would help the user understand that moving to these locations is taking a route that increases their attack angle.

ISSUE 15 - Inconsistent Mechbay Math and lack of saving loadouts
SUGGESTION - I have taken 2 mechs of the same Chassis/Variant (TDR-5SS) and attempted to duplicate 1's build in the other, using the same weight items and distributing the armor similarly. I have had instances where armor was off by 0.06, and I've had instances where tonnage was off by 1.5T. Adding the ability to save chassis loadouts for similar variants would be nice to quickly duplicate one build to the other (if possible with similar gear quality)

ISSUE 16 - Movement UI does not convey navigatable terrain easily
SUGGESTION - I have had times where I moved a Mech (w/o JJ) towards a location in hopes that, beyond its movement range for that round, would have a path that allows me up steep terrain (but not a cliff). Only to realize in the next round that it has no pathing my Mech can take. It might be nice if we saw movement times beyond our movement range. Tiles outside our immediate movement range could be yellow in color, and tiles that would not be traversable could be hollow squares. This would have immediately indicated to me in the current movement round that the Mech would not have been able to route up this embankment, rather than having to go there, realize that, and turn back next round.

ISSUE 17 - New sensor contacts prematurely ends remaining movements for out-of-combat units
SUGGESTION - Not sure if this is a bug, but when out of combat and coming across new sensor contacts, randomly, I may or may not be able to complete the remaining move orders for my units. When not able, the button forcibly turns to DONE and some of my units end up further behind others when the combat round starts.

ISSUE 18 - UI is confusing in indicating Mech weapon range and optimal conditions.
SUGGESTION - With a Mech with LRMs and ML's, the UI is very confusing when I'm moving that unit to knowing if (A) my ML's are in range, and (B) are they at optimal or suboptimal ranges. I think color coding the current unit's weapons while in moving mode would help. Gray = Out of range or view (when facing Mech), red = out of range, yellow = in range, but sub-optimal. Green = in range and optimal.

[...more below]
ISSUE 19 - When moving next to friendly units, accidental clicking takes user out of move/facing mode
SUGGESTION - During movement/facing mode, don't allow clicking of other Mechs to take you out of this mode. Instead, require the user to explicitly escape from this mode first before being able to select other friendlies/enemies.

ISSUE 20 - Keep up the great work!
SUGGESTION - Cause this game is fun as heck!

Sounds really good to me. I like the game much but your suggestions mostly would make the game even more enjoyable, asked myself alot of them, too. Shops and toot lists can be very long in the end, so there a good filtering system would help as would faster loading times, too.

Make sure to crosspost this to the official forums, as the devs to my knowledge do not read the GoG ones.
As a matter of fact, this forum wasn't even linked properly through Galaxy until a few days ago.

Good suggestions.

I`d add :

1. Better and brighter hair colours including white. You can now make a fully white Mech, but I can`t have someone with white hair or very blonde hair? Seriously?

2. Allow us to skip the Tutorial mode as an ingame option.

2. Allow us to ignore the whole story and just have or even buy the ship when we can afford it.

3. Also if they insist on more stories no more "Illusion of choice" nonsense. I hate being told I have a choice when the whole thing comes round to what they want to do anyway, leaving me thinking, "That`s not the decision I made!"

4. I`d also like to have or even make my own randomised ship crew, engineer, cartographer, etc, but I guess that`s unlikely.

p.s. Paradox will likely never take any constructive criticism here since they happily remove or bann people that hint at any kind of real criticisms.

Some pretty nice suggestions there.

Well thankfully it's not Paradox that are making/supporting the game.
If we are forced to go trough their forums to reach Harebrained Schemes it is of course a bit of an issue.

White enough for you? They added some extra customization options and brighter hair colours in the last patch.

No. That`s what I`m talking about.