I can find no backup for point 1. Currently Democrats out-register Republicans by 700,000 voters, even though more new voters have been registering as Republicans. Moreover, Biden has maintained a steady lead in Pennsylvania outside the margin of error.
https://www.newyorker.com/news/campaign-chronicles/the-new-republicans-of-pennsylvania
Points 2 and 3 are mere guesses. The enthusiasm
against Trump that I've seen is off the charts.
Point 4 is blind hope. A fraction of absentee votes always get thrown out. As for election day turnout Republicans had better hope there hasn't been a resurgence of the virus that scares even a large number of Trump voters into staying home.