Is there a quick way to replace just the dust boot without disassembling the rear caliper while it is still attached.

I cut mine up with a wire attachment.

 

I was able to do it very easily and quickly.

Is it possible to break the rear caliper by turning in the piston too much?

When I was putting it back in I kept rotating it and didn't notice it had bottomed out and it it would still spin, but not go in further.