I would guess the first step is to check that RF caliper. Can you get it unstuck? Is it just a build up of rust on the outside or did the piston actually sieze because of moisture in the brake fluid?

You need to also determine if the rotors can be turned or are they bad & need to be replaced.

Once those questions can be answered, make sure you have all the parts on hand so that you aren't up on blocks for weeks & weeks waiting on parts.

This is all my 2 cents - I'm not a mechanic or a brake expert.