1- You wouldn't have to- all it takes is an enemy with political pull and you'd be in his shoes.
2- Actually, it's established precedent that he can't be charged in office.
3- No, unseemly and not criminal are not impeachable. There was no underlying crime in the Russia probe and there's no underlying crime here either.
4- No, again, these are rules the Democrats passed in their caucus earlier, without Republican input. If they followed the rules and precedents previously used, Trump would have the right to confront his accusers, and there would be no secret trial.
Read Dershowitz's column today, and educate yourself. Facts are facts, and if the truth comes out you will no doubt deny it.