Actually I think the only thing you can't really change in FWE is the damage increase, weapon and ammo rarity, and stimpack rarity. Means just starting out in FWE is a challenge because you need to do everything a certain way or you run out of ammo and stimpacks and are pretty much screwed. Everything else you can change.
Dude, I don't want to sound defensive or anything (I'm not a FWE dev, after all) but you can adjust each of the things you mentioned above via the in-game menu; global damage multiplier, ammo rarity, chem rarity, and even misc loot rarity are all individually adjustable; the whole shebang. The only thing that I'd like FWE to still include is global 'hand-placed loot' rarity, as per Savage Wasteland. Even with the FWE reduced ammo spawns in miscellaneous boxes and such, there is way too much hand-placed ammo available in the game world if you just have the patience to do some exploration. Like with my current character, I have not once had to purchase ammo from a vendor; not once! By the time I reached level 12, I had roughly 1500 5.56 rounds in my inventory because I started using laser weaponry at level 7...