And the second question: is it recommended to cut the back of the frozen/thawed mouse's back to aid in digestion to help them grow? I've seen it work for corn snakes, but I was wondering if it's the same thing with BPs.
That smells like one of those "old-school" concepts that are long outdated. You said you've seen it "work" in corn snakes as well- is there data to support that? Did you have a control group to compare to? Be careful about making those kinds of statements, this is a good example of how bad info gets spread around.