Those promos will count towards point reduction.
I suggest doing both, to ensure we definitely see it.
The rules ask that people participating post a fic, so we can’t accept an outline. But even part of a first chapter, so long as it was posted as per the rules would guarantee your participation and entry into the challenge. I suggest writing what you can and posting that – chapters are allowed to end on cliffhangers.
Only if you make this very clear in your reblog. And perhaps give a tiny account of your time travel adventure.
This would not be considered cheating.
Manipulating it so that loads of pseud accounts/usernames you control also leave kudos would be considered cheating.