Crank sets aren't english threaded. BB shells are.



This is a bb shell. The bb screws into those threads there, and of course the threads on the bb have to match the threads on the shell or it won't work. English threading is one standard for bb shell threads and bb threads.

Think of a line from your front hub to your back hub. Bottom bracket drop is how far below that line the centre of your bb shell is. On a lot of track frames, bb drop is somewhat less than on a normal road frame, (i.e. the bb is higher). This is to keep the cranks from striking the banking of the track when you're going slow.



Sheldon Brown's bike glossary is an excellent place to get answers to these kind of questions: it's quicker than this forum and generally a lot better (no offense to us).

http://www.sheldonbrown.com/glossary.html