Wheelset: Mavic CXP 22 laced to formulas are probably your most cost-effective and durable option. http://wheelandsprocket.com/itemdetails.cfm?id=7103
Get Deep V's if thats what you think they look good...most kids are riding them for that reason, not really based on their performance.

Brakes: Long reach, obviously. Plenty of inexpensive options.

Crankset & BB: Get a single speed crankset as well as a corresponding BB for chainline's sake. Most cranksets will say what spindle length you need in their description. I don't know anything about cottered cranks... but those don't look very durable.