I'm flighing home from phuket to brisbane with a connecting flight at bangkok. I believe there is only about 1hr 20mins time between the flights at bangkok, as set by thai airways, will this be enough time? How does this all work?

Also when i firstly arrive in bangkok i have a 'personal vehicle transfer' booked.. will there be some guy waiting for me with my name on a sign to pick me up and take me to my hotel? is that how it works?

If you have only one hour and twenty minutes between flights at BKK why are you concerned whether or not your personal limosuine is going to be available to take you to a hotel.

Change overs ie more then one. Into Thailand ask the hotel which door and if the sign is the hotel name or yours, they sometimes use a van and pick up many people. Out bound lay over, not sure never done that in new airport yet.

Your 1hr 20 min connection at BKK will be no problem at all. Even if your flight from Phuket gets a delay the Thai ground staff at Suvarnabhumi are very good at handling connecting passengers. I once made an international to domestic connection in 14 minutes due to an inbound delay. My checked bag made the connection too.