I'm going to swap out some old cottered cranks for a new set of cranks.

So, I have to remove the cotter cranks, and the bottom bracket.
Then I'll need a new bottom bracket with square tapers and a new crankset with square tapers, and thats it, right?

For the bottom bracket, do I need to measure the width of my frame's bottom bracket shell, or are they more or less universal and thats what the adjuster cups are for?

Thanks very much!