Welcome! And glad you're enjoying the game. To your questions:
1. You can actually just discard enchants and for most of them (all the ones you find out in the wild, just not the ones you can buy) you'll get enchant progress back. This is basically a portable incinerator.
2. Head enchants are just for things that affect what loot you get, and at the moment I do believe that is just limited to the seekers. The reason for this is that when something loot-affecting competes with something gameplay-affecting in the same slot, then to play "optimally" people will use the gameplay enchant until the last second before loot is given out, then switch to the loot enchant. That's annoying and fiddly for players, so we made a slot just for the loot-related stuff to keep that from happening.
3. You can put the heatsuit on and off at will, actually. Just right-click it (or otherwise use it) any time, and you can put it on and off as much as you want.
Cheers!