carbon - For get it, go with steel. You might even look at the vintage board for advice on a 1970s frame.
Consider an internally geared hub, much less maintenance than a derailer.
http://sheldonbrown.com/harris/hubs-internal.html
Consider Phil Wood hubs and BB.
I like those saddles with springs on the back, and handle bars that have me sitting upright.
You might also consider a folding bike like xooter swift (ask for steel frame)