Regarding the valves, both do work. I find that Presta valves come on both high- and low-end bikes. My daughter's $299 Raleigh Alysa has Presta valves and the GT Aggressor Pro that I bought for her at Dick's Sporting Goods (also $299 on sale) has Presta valves. I usually drill out my Presta rims to fit Schrader valves, and standardize on that design. The thing I like most about Presta is the external threads and the lock nut. These are available in Schrader, though can be harder to find. Specialized makes tubes with fully threaded Schrader valves, and I get these at my local Specialized dealer. Presta definitely have an advantage with narrow rims -- it's easier to cram both beads and the valve between the rim lips if the valve is narrow. I tend to ride wider wheels, though, where this is not a concern.