I know enough to work on my bikes with what I have, but if something breaks and I have to replace it, I might be screwed. So here is what I need to learn.

1) I have no idea the size of my two bikes. I got them both for free or for trades. How do I measure them to know what size.

2) Bottom Brackets. What is the best way to be measuring for the proper BB? Anybody have any reccomendations for an old Motobecane conversion?

Thanks. Any info helps, so if there is a resource I just overlooked, then please, just point the way.