I have never really played an evil character before so I wanted to try it, but it seems like a lot of the evil quests require lock picking but that is a technology skill. So does magical ability interfere with lock picking? Or vice versa?

you can pick locks either with magic or tech. Lockpicking skill is tech based, but for magic casters they have a unlocking spell that you use instead. The higher your magical affinity the stronger lock you can open with the unlocking spell.

The difficulty for picklock skill is based on different factors :
-the difference of level between the character and the npc/chest,
-the difference of TA between the character and the npc/chest,
-the training (master) can half the diffculty.

Paradoxically, a mage with 100 MA is immune to technolgy items and therefore ignore the penalty from TA for picklock.
I play a mage thief with 100 MA and master picklock and every chest opens very easily.
Note : there's still a 1% crit fail. Unlocking Cantrip is a noisy and aggressive spell, it'll turn npc in range as hostile.
Personally I don't use it, I've never been able to open any merchant chest with this spell.

as you said, "in range". you easily can use your spell to unlock stuff from a good distance, and not near anything that will turn hostile. Actually much easier sometimes to do it this way than to unlock a object right at the object. You can sit far away , yawn, and cast a unlocking spell to open anything you can see, and since you aren't even close to the chest, nothing near the chest/door goes hostile because you aren't close to them.

Already tested many times and I confirm that it's in range of the target. Many merchants stay close to their chests, i.e. in range.

Wait a second. If your lock picking skill is based on your dexterity, does that mean Agility of Fire can boost your lock picking?

Yes.

You can use Agility of Fire to boost your dexterity and add 1 point in picklock. Then turn the spell off, your point in picklock will remain.
It's a trick many are using to put CP in skills without maxing the according stat.

I doubt it. Having played enough Arcanum, I think a majority of the quests, evil or good, can be done without the need to pick locks. Which events are you having trouble with?

Right now i am trying to get the journal from Gilbert Bates but I can't get the chest open.

I want to play a magic type character so i am trying to figure out if i should spend points on the lock picking skill or just get the unlocking spell.

Given how few character points you get it seems to make experimentation kinda dangerous because you end up with a character who can't really do anything.

if your a mage, you pick the lockpicking spell. Its the magic variety of the tech based lockpicking skill. There isn't any reason to take a tech based lockpicking ability when mages get a magic affinity based lockpicking ability.

Let's do the maths.
We suppose you start with a male human (8 in each stat) and no background.
To be a strong mage, you want WP 18 (cost 10 CP) and 100 MA.
Each spell gives you +5 MA so 20 spells = 100 MA (cost 20 CP).
Now we suppose you want to become Master Picklock too so that's DX 18 (10 CP) and picklock 5 (5 CP).
But each point in picklock is going to drop your MA down (-6) so you're going to add 6 spells to stay at 100 MA (6 CP).
Total CP cost : 51.
You have 13 CP left (between lvl 1 to 50, you receive a total of 64 CP), that's not a lot but you can also find items to help such as the Dark Helm (+20 MA) which can then save you 4 CP.

Note : on the vanilla Arcanum, the Dark Helm is bugged, i.e. : each time you wear it you stack +20 MA and -20 Alignment (up to the max, of course).

Except that the lock picking spell makes so much noise you draw in half the guards in Tarant. I am starting to wonder if this character is another dud, I don't have the skills to pick locks quietly, don't have the power to fight my way out.

sorry never had any problem with mage lockpicking spells. Played through a dozen times many as mages, and used spells on what ever i wished. Never found a lock that i couldn't find a spot that the guards weren't alerted. I either waited until no guards were near, or i cast from a distance where no guards were at. Sorry, don't know what to tell you, i never had any problem being a mage with the lockpicking spell.