You are right, if you do it properly, you may only need to bleed the new caliper. However, unless you have changed the brake fluid in the last few months this is a good time to do it all. I would.
I know that a T-47 is needed to remove calipers on our cars, but I don't remember if that is for the front or rears. I hope someone else joins in. This is a frequently asked question.
