1. why were republican poll watchers not allowed to watch the vote count?
They were allowed to watch.
What they weren't allowed to do was change the votes.
2. how did Trump's vote totals go down in the middle of the night?
They didn't. The margins increased. So Trump's % of the vote declined, not his vote totals.
3. why did hundreds of americans sign affidavits attesting to witnessing vote fraud?
Because they're sore losers and not a single one of those people had the courage to testify in court under oath because then they would be guilty of perjury since none of them actually witnessed any voter fraud.
They're lying that they did. That's why they won't go into a courtroom and testify under oath.