blimey i feel like a school teacher, ok to answer one question a time.
first jim, chemical strip or sand blast, both around 10 pounds on mates rates

ratty, yes you can powder over powder. the only way to get a good finish is to
coat the frame hot, i done brownies race inc last friday and wasn't happy with
the first coat because the rear end was pitted so recoated it, therefore
powder on powder

also romblokes, oldsky, my own frame and a few more
members have had two coats

back to jim. does it need stripping