I suppose stability only as the 64 will use all of the ram.For a game the size of yours, probably 64 will be a safe bet.
Lol, but i doubt 32 will go anywhere in the future.
I think dll bind is possible in 64bit but i have only seen one example that was left a mystery.This game:
The files are long gone for download, but i still have them.And in his editor folder in the binaries>win64 he does have a UserCode folder with two dlls responsible for saving in the game.When playing the game in 32bit or 64bit you can save the game (player position and picked items) and when used the 64bit exe and 32bit, bought can use the same dll to load the game.
But i never managed to understood how he did it.If interested, i can upload the two windows folders and the uscripts for you to try and track it, but i dont have the source for the dlls.I suspect that the dlls in the 64bit folder are 32bit ones and using scaleform and the uscript> he calls for the dll in the 64bit folder that by it self calls the one from the 32 bit folder.But its just a theory.