On Icewind Dale my Bard can play a song called Tymora’s Melody that gives +1 luck and +3 to saving throws do saving throws have anything to do with not taking damage? (save vs death?)

Saving throws are used in a variety of situations, often around spell and trap effects (and resulting status effects). If you look at spell descriptions you'll see effects mentioned vs a type of saving throw that can be used to resist or mitigate the effects. In very general terms making a successful saving throw is how you keep bad things from happening to your characters.

What about an attack by an orc in the Orc Cave in Easthaven

If that's a physical attack, then only the +1 luck affects whether it will hit or not - that's against the THAC0 value. Luck effectively enhances it.

The saving throws are against effect which permit saving throws. If the attack has some elemental damage attached, like fire, then a saving throw will affect how much of the damage, if any (fire ST usually halves damage) the character will receive.

In brief: THAC0 affects if you will get hit, saving throw affect if the damage/bad effects can be avoided. Physical damage has no saving throw by itself.

Attack chance to hit and damage are handled differently. As Titanium spoke to, attack chance to hit is governed by armor class (AC) and THAC0 (To Hit AC 0)- for your own characters lower is better for both AC and THAC0. Damage is determined by the damage rolls for the attack (each weapon or enemy attack has a damage range it can roll), along with any damage mitigation you happen to have (damage mitigation for your own characters is pretty rare, so you won't run into this very much, although you'll see it more on certain enemy types vs certain types of damage). For enemy attacks, saving throws usually only come into play if there's a status effect associated with the attack (e.g. poison on hit). In such a case there's a difficulty class (DC) for the check, and your saving throw for the particular check is added to a d20 roll to determine if you resist the effect.

Do spell buffs stack with bard songs and other spells?

Oof... it's been quite a while since I played anything based on AD&D rules, and I can't recall how buffs from multiple sources were handled. Best advice I can give is to check your character sheet before and after applying a stacking buff, to see if what's there indicates the buffs stack or if only the highest value from all sources is applied.

Best answer is: sometimes.

Why is this on the general discussion forum and not the Icewind Dale series forum where it belongs? Actually, it sounds like you may have your editions mixed up.

In Icewind Dale and other 1e/2e based games, there's no difficulty class mechanic; each character has a saving throw value in each category that's determined by class and level. Roll under, and the attack is saved against; roll over, and it isn't. (I don't remember which case rolling the exact value falls in here, but I think it might be a successful saving throw in this case.)

In particular, this means that:
* Higher level characters are more likely to successfully save.
* Higher level casters are *not* more likely to make their enemies fail their saving throws; the caster's stats don't matter here, either.
* Higher level spells are *not* less likely to be saved against, though there are a few spells that apply modifiers to their saving throws. The general rule is this (though there may be exceptions):
* Different effects stack with each other, so you can have a character benefit from Emotion: Courage and Emotion: Hope at the same time.
* In the Classic Edition, multiple instances of the same spell usually stack (so you can stack multiple Emotion: Courage spells to get a big bonus to hit and damage). In the Enhanced Edition, however, they usually do not (so multiple Emotion: Courage spells won't give a bigger bonus, though in this particular case you still get the 5 hit points of healing every time).

Probably was mixing things up with 3/3.5e mechanics. Thanks for the corrections.

You're welcome.

With that said, Icewind Dale, with the Heart of Winter expansion (included in both GOG versions, so chances are you have it unless you have the original disks), does introduce some mechanics from 3e, albeit not always in the best way. From what I can remember:
* Evasion: Rogues who save against certain attacks (like Fireball) take no damage rather than half damage.
* Sneak attack: Not enabled by default (and replaces backstab when it is enabled), but lets the rogue do extra d6 of damage in the right circumstances. I believe it's more limited than the version in actual 3e.

(It's also worth noting that Baldur's Gate 2 brought in a few classes from 3rd Edition, and Icewind Dale Enhanced Edition incorporates those classes. Also, note that Icewind Dale 2 is based around 3rd Edition rules, though some of the implementations there are a little strange (like the way spell resistance is handled).)

Whoops, I actually kinda merged those two together. But I keep forgetting it's not an easy system to explain to someone at all.

And then, you have the editions :-D

From memory, Bards can cast any of their spells of a certain or lesser level, but only so many times per rest (usually called "per day", but it's really per rest). So to get your spells back, simply rest.

Are you playing the Enhanced Edition? If so, and the character is a Sorcerer, then the character's spell casts are allocated per level, rather than per spell.

It's like the magic system in Wizardry 1-5 or Final Fantasy 1 or 3, if you've played either of those; the spell casting interface just doesn't make it clear.
No, that's not how it works in 1e/2e based games like this one. Bards only got this sort of casting in 3e, and even BG2 (which IWD:EE bases its mechanics on) doesn't let Bards do this.

Furthermore, even in most 3e games, the "or lesser" part isn't actually implemented; run out of 1st level spell casts, and you can't cast any more even if you still have some 2nd level spell casts remaining.