What should we know about extending our stay in Thailand with a tourist visa?

Hi everyone, this will be our first trip to Thailand for my family and me. We hold US passports traveling full time since July 2018. We are in Spain now going to get our 60 day tourist visa in Madrid then extend for 30 days. We are staying at a friend’s house and would like to stay 9-12 months.

My questions are

- seems like everyone coming in on tourist visa needs to have proof of onward travel plans, we don’t know exactly when we will be leaving. Should we have cheap flights booked towards the end of the first 90 (60+30) days?

- can we do 90 day extensions on tourist visa to stay up to 1 year?

- if we want to do tourist trips out of the kingdom every once in a while, do we just get a re-entry permit before leaving?

- our friend will be registering the house in order to keep up with the TM30 reporting.

Thanks so much for keeping this fb page so active!