But you're not talking about fast track. You're talking about VIP fast track (safe entry) where an agent syncs up with immigration to guarantee your entry.
there is no visa to move. The visa is on a pdf document sent by the embassy and that document has a passport number on it. That's why you need both the old and new passport.
The red lights in Thailand seemed longer to me, but really depends on the traffic.
How about actually asking a real question? Wait time for what? What visa? What is your passport country? Any other details that might help someone understand both the question and the details surrounding the question.
Yes, get a local plan. And it depends on the carrier, but yes generally wifi calling will be local.
If I were you I'd consider looking at switching to TMobile if it's practical. They offer free international data. It's not enough for you to not get a local SIM plan which you'll need regardless, but means you don't have to be scared of something going wrong and you getting a $1000 phone bill.