alignment is always necessary after any front end work. You shoudl be able to do the ball joint yourself. You car doesn't need to be properly aligned to pass inspection though if that's what you're worried about. They don't check that. Plus alignments aren't all that expensive.

Just a word of advice, be patient. When I replaced my rear main and my clutch it was a bear getting that baby lose on the drivers side. Passenger came right off.