We bought and ordered our tt online and faxed signed paperwork between us/dealer; credit card was our downpayment. Final paperwork was completed when we did our PDI/picked up trailer. When we paid the money still owed, then physically took delivery of the tt, we activated the insurance on the tt.
As for extended warranty, Jayco has a two year warranty. I read a lot on different rv forums, and the consensus was to not purchase the extended warranty. We opted not to.
We didn't do a "trade in" so I can't share any experience there.
Wow, the time went by fast, I bet you guys are pretty excited about finally getting the tt!
(One other thing I should have mentioned is we paid cash for ours so we didn't have to worry applying the insurance til we picked up the tt)