What's wrong with using an official initiative variant? And bonus action for potions is a very popular homebrew rule in the pnp, I think it's even suggested in the rule books as I remember reading about it.
And the BG games didn't follow AD&D 2e rules very closely, it used a bastard version of 2e and 3e with tweaked rules everywhere. That's why BG2 has 3e classes in it. I find it funny you call out Larian for monsters, when BioWare was just as inventive with them...
As for mage hand, it's pre-alpha, it was bugged. Swen mentioned it. It wasn't supposed to behave like a character and it wasn't supposed to have shove but throw (which it can do for things weighting less than 10lb by the rules) but the throw didn't work in the build he had.
In five year and many group, here in italy, never seen the homerule about potion used in game. The initiative variant, nothing wrong per se, only that with all the other change is a little annoying. BG2 come after 3.0, so the mix, BG1 (not EE) doesn't have classes or kit aother than the standard, also doesn't remember monster in BG1 with stat changed, exept maybe werewolf due to lack of silver weapon (and only in the expansion)
Sarevok stats and resistances makes no sense for a level 15 living human. The revenants in the games have 3 attacks per round, instead of 1 (going by the AD&D 2e FR monster manual I'm looking at) with a bunch of other little changes, like more HP despite being level 2, better THACO, etc.
