Do I need to remove the entire armrest to swap this plate?

Depends on the design of your specific assembly. Most latch plates unbolt from the armrest without full disassembly, but test-fit the old one first to see how it's mounted. If it's fastened from inside the console, you may need to lift or partially remove the armrest.

Will this work with my existing console armrest, or do I need a new armrest too?

This plate is designed as a direct replacement for the latch mechanism on your current armrest. If your armrest body is intact, this bolts right in. Only upgrade the armrest itself if it's cracked or damaged.

Is any prep or painting needed before installation?

This arrives ready to install—no prep or paint required. It's a direct functional swap for the worn or broken original.