Do I need to remove the entire door panel to install this?

You'll need to access the door from the interior side to unbolt the old handle and bolt in the new one. Most owners can do this with basic hand tools and a panel removal kit in about 30 minutes.

Will this work if my keyhole is broken or missing on the current handle?

Yes—this assembly comes with a fresh keyhole built in, so you get a functional lock cylinder out of the box. Your existing key will work once installed.

Does this come with the internal door latch mechanism?

This is the external pull handle and trim only. The internal latch stays with your door. The handle bolts to the existing latch mechanism—no disassembly of that part needed.