1) around $1,000 is a great place to be budget wise for what you've described as your plans for riding!

2)regarding racing. Just do it! Click on the Racing Subforum to get some more info. If the coach is asking you to join his team, ask if team members get special deals on bikes, accessories...etc. You may want to hold off buying a bike until you find out what kinda deals you can get through the team. Other than that all you'll need to start is a helmet (should already have) and a NORBA license, which you need to race any santioned event (get those at the race registration tent).

3)You don't NEED disc brakes. Unless you are riding a lot of downhill sections. Vee-Brakes (linear pull) work great for 99% of what most people ride. Plus, if you're planning on racing, they're lighter weight and easier to adjust. I will add that discs are sweet, but cheap ones aren't worth the hassle.

4)Travel was well described in an earlier response, but stick with 80-100 mm for XC and all around riding!

5)Clipless pedals are a definate upgrade once you get comfortable on your bike. They'll help your pedaling effiency and will make you a better rider. However, as a newbie, stick with regular pedals until you get real comfortable on your bike. If your bike comes with clipless, keep em, but buy a second set of pedals. BTW, you need special shoes as well!

L8R