Power Strike does that "difficulty change" thing, too. Makes me think the only hope of beating the game is not to shoot at anything except the bosses.
What is weapon zero? You mean the gimpy default weapon that I have to collect 6,172 P's to upgrade to two shots, and then 6,172 more P's to upgrade to three shots and so on and so forth?
What is a 1CC? 1 credit completion? (Wild guess).