Yes but you don't win by campaigning on never being able to achieve anything. In this specific case, you get in, show you can do a certain amount of stuff with your hands tied and then you win the midterms. Most of his policies are remarkably popular anyway, who knows what might happen.
I agree, and if he were to win I imagine the house will be broadly supportive of implementing the agenda he'll be pushing.
Actually I just re-checked and this year and 2022 are actually the years where the Dems can win the senate , there are nearly twice as many republican senators going for reelection in those election years as dems. So you never know. The big slate of sitting dems won't be up for reelection till 2024.
That whole 6 year term thing they do is weird.