1.) You can't use it for every map because it sometimes prevents triggers from triggering, and the route remains more or less the same cause you still need to accomplish all objectives to exit the level. It isn't extremely game-breaking but you don't have to worry about HP in few levels where it can be used. (I didn't test it in every level.) I remember that it can't be used in crypt2, first part of escape2 and baseout for example. Also, using save/load is sometimes slower because it can freeze enemies in doors and tight parts of the map / they can't run towards you (which is problem in first part of escape2).

2.) I am up for both.

3.) Most games use newest, official version available, also 1.00 save/load mostly crashed the game (like, 70% of the time. :D) for me which isn't very nice. So I would prefer 1.32 (steam official) or unofficial ones.