1 - much respect

2 - IMO, carmichael's training books are pretty superficial, kind of the equivalent of "training for dummies". Get the friel training bible and the allen/coggan training and racing with a power meter (even if you dont have a power meter) book for better discussion of physiology and its relationship to training for racing.

3 - crits, especially at the cat 3/4/5 levels, are about cornering, accelerating, positioning, and sprinting. given your specific circumstances, I'm not sure how to best utilize your physiological constraints, but would suggest thinking about those skills when you're training.

4 - if it's in your budget, seeking out a training specialist with experience in amputees would be aces

5 - practice, keep your attitude positive, practice some more, and keep the bf.net racing subforum informed about your progress. I can only speak for 1 of us, but am rooting for your success!