Do these come with bolts and clips to attach them to the door?

The assemblies use factory mounting points in your door frame. Bring your door panel apart first and check what hardware is already there — you'll likely reuse what was holding the old regulator.

Can I install just one side if only one window is broken?

You can, but these are sold as a pair. If only one window needs repair, you're buying both — consider replacing both while the door is open since you'll be doing the labor anyway.

What if the window won't go up after I install these?

Most issues come from improper seating in the door frame or a bind in the track. Dry-fit the assembly, check that the regulator arm moves freely, then secure it. If the motor spins but the window doesn't move, the regulator isn't seated right in the track.