Hey guys, I'm relatively new to mountain biking (I've been riding bikes since I was about 3 yrs old but I've only been getting serious with mtn biking this last year)
I found a 2004 (?) Gary Fischer Wahoo at a local garage sale for $35, I jumped on the opportunity because I really like the frame but it is unfortunately a fully rigid frame. Before I step up to some more difficult trails I would like to change some things on the bike and I was hoping you could help me out with what to buy...

1. It's a 21-speed bike, I have been riding a 10-speed for most of my life so it's probably because I'm conditioned to that but I feel like 21 gears is way to many to have to shift through to get from the lowest gear on the bike to the highest gear. I want to replace the derailleurs any how so is it possible for me to buy a 10 or 8 speed set of sprockets for this bike?

2. Unfortunately the bike has a fully rigid frame which I'm not a huge fan of. I'd like to replace the front forks with something with suspension, I really like the rock shox but I figured I would ask you what's the best bang for my buck regarding shocks?

3. Puncture proofing the tires. I've used the bike on a few multi-day treks already and I'm always paranoid that I'm going to run a cactus over or hit a goat head or whatever sharp objects I encounter. I carry everything I need to repair/change a tire with me when I ride but I would like to be able to avoid the problem altogether if possible. My plan is to buy extra thick Kevlar tires, puncture pads that go in between the tire and inner tube, and then the goop tires. Do you know of any better solutions to the issue?

I think that covers everything.
Thanks guys.