Definitely update the driver for one - when I got my Firepod (at the time I was using Sonar) I had a hard time getting it to "name" the inputs correctly until I updated drivers.
Second, i had the same issue when I first switched to reaper - I enabled ASIO inputs, selected the Firepor, and was then only given two channels to select. All I really did was close it, then boot it up again and lo and behold I could then change to 1-8. I might have had to open and close it again - I think the issue was Reaper couldn't "look" for additional channels when I first switched to the Firepod, because it was only configured for two when I first booted it up. When it checked on next load, it found all 8.