DH=dumb husband?
Don't worry so much about the whole 26 vs 29 thing, the differences are way too subtle when you're just starting out.
Your fork sounds like it has too much rebound, if there's a knob on top of one of the stanchions try turning it and pressing down/up on the fork. Alternatively, get a shock pump and lower the pressure. Your LBS should be able to help too. They should have better trail suggestions too if any of the mechanics/salespeople mountain bike locally.
The best way to deal with ruts is ride above them and bunny hop over them if you need to cross one. Bunny hopping takes some practice though.