OK, I finally spent some time with it and figured some things out.
Hitting SELECT + I (maybe it's SELECT + II, I can't remember) will kill your dude and let you re-spawn at the last checkpoint.
The game is HARD, and you can screw yourself pretty quickly.
I'm not sure what all the bonus objects do yet; the knife is pretty self-explanatory (throws a knife in front of you), the mining pick will let you dig through soil. I have no idea what the shoes do (perhaps let you walk over explosive mines?), or what the evil mask does (scare enemies?).
I like the game, but it is a bit confusing. If you can assemble a house (special parts), your guy will stop and knock on the door, but it doesn't appear to do anything.