1. Just about everything here can be important. Primarily processor and RAM. My 2.5 Ghx 1 GB RAM desktop does an adequate job for small projects (under 16 tracks usually) if that helps as a point of refence. Many many DAW will be more powerful than mine. A fast hard drive (at least 7200 RPM, and the cache size (or is it buffer, i forget) can make a big difference as well. Multiple drives, one for the programs and another for data can be good, keep the data drive defragged. BUS speed can factor in here as well, but this stuff is less noticable and more for high tech types to be concenred with.
2. firepod is pretty well thought of as an entry piece of epuipment, what software were you considering? I got the Layla 24/96 which is discontinued and has no preamps, but was much cheaper as a result, and i have heard too much about everyone and their brother ready to upgrade their pres on their interfaces, that i decided to go for the functionalioty i wanted and use the extra money to get (not much) better pres and other dedicated equipment.
It can get as complicated as you want in determining a start point, you can post the type of stuff you want to record, how many tracks at once, what kind of (non computer) equipment you have etc. This will give people somehting to work with with specific info.
I like the idea of starting simple (especially with investments) and get some hands on experience with what you have, then figure out what you really want and go from there to determine what you really need to invest in. Sounds like you are moving int hat direction.
Daav