"I'd go with a rim brake cross bike so you have a built in set of extra wheels off the bat.
What tire size you can fit on a bike is mainly dictated by the frame. That is, how much tire can you shove in the fork or between the seat and chain…"
"Also, don't blow your budget on the bike. Chances are the tires on that bike suck and at some point you're going to want a second wheelset (and tires). Frame and components need only be serviceable on a cross bike. Tires are where…"
"You can pick up a tubular wheelset for ~$250, maybe less. I haven't paid any more than that for any of the 6 wheelsets I have. So think about that in you budget. Gluing wheels is a reasonably easy thing to do. There are a lot of good tutorials…"
"Concur, technique is off if you are hitting yourself in the head with your saddle. The book Skills Drills and Bellyaches has some great photos (and text) demonstrating the correct method.
The muscle issue gets better with time as your ride cross…"
Funny... I had a 42, single ring, in 2007. Always felt I wasn't able to keep up on the road sections, and wished I had the bigger ring. Went to Nats and got outsprinted (for 27th...) Went to the 46/38 for 2008 and had one of my best seasons ever. I've been thinking of going to a 44/36, though. Been struggling a tad this year with the climbs. Got married, took time off, had family in town... and it's all crashing down now!
See you on the start line somewhere along the way!