its tough to say what length is going to be better for you until you ride. its about whatever is comfortable for you. i started riding a random bike i bought complete and started replacing parts that i figured out were making me uncomfortable or sore. maybe start out with the shorter stem so you arent stretched out as far...those lengths arent like a seat post or something that wont fit on certain frames if that makes sense. the black are more expensive because they are black, no real reason. my girlfriend has that wheelset. its a good starter. and you can put any size freewheel or track cog on you want. those formula hubs are great. you dont want to start out with crazy expensive things until you figure out exactly what you like.