You’re using “on arrival” in a confusing way. There’s something called “visa on arrival” which isn’t what you’re looking for, so make sure you don’t get confused.
A SETV lasts 60 days and then
*****
+ days after entering the country you can apply for an extension. That’ll add 30 days to the total, regardless of when you ask for it.
Strange, to me it only asked for 3 documents: flight, ASQ and insurance. For the preapproval just the passport if I remember correctly.
I did book the flight and even the hotel but nobody ever asked me for that (except for the hotel address, but not the actual confirmation, even on arrival)