There are a number of good C resources. I'm listing a few below. I also recommend Harbison and Steele's C: A REFERENCE MANUAL and, if you'd like to be a C monk, Peter Van Der Linden, EXPERT C PROGRAMMING: DEEP C SECRETS.
Beej's Guide to C Programming
Jacob Navia's "A quick introduction to the C language"
Embedded C Traps and Pitfalls
There is also the entirely useful and intriguing
Ch dialect of C. This is C implemented as a powerful interpreter, so it can be used for scripting as well as programming. It affords all the capability of C, plus the dynamism that comes with an interpretive environment, including the ability to debug more readily. While it
is a commercial product, the
Ch Standard edition is free for the download. It also offers both heavy numerical support and the for-purchase
Embedded Ch, which lets runtime call a Ch interpreter for script execution
with certain advantages.
Ch is also available for Unix/Linux and has packaged with it all your favorite Unixen commands available from the WinXP shell.
I know it would be breaking the FRC mold a bit -- and it's certainly not a task for a Rookie Team -- but basing a FIRST entry upon Ch and its world would be most interesting.