Doesnt even need to be a air ticket I used a train ticket from the boarder of hat yai to malaysia, was accepted no problem and the ticket cost only a few quid.
Yeah there are a few grumpy ones there and suvarnabhumi but aslong as you are not overstaying or breaking any visa conditions I would just keep calm, let them throw their little hissy fit and eventually they will stamp you in or out. I got stopped recently departing from bkk and pulled to a seperate table for 20 minutes I kept a smile on my face the whole time knowing the fuss was about nothing, and eventually she stamped me handed back the passport and then started having a go at another tourist. It is what it is but as i said if you are not breaking any rules just take it in your stride.
Going to assume this was Bangkok? Ive had a few like that, even had them scowling when I depart even though ive never overstayed and everything is within legal limits.
As others have said rent first and get a feel for things, living in thailand is quite different from a vacation. After a couple of years and your still happy then you could look into purchasing a villa in a company name but someone else will be better placed to advise on that matter.
I had a residence in jomtien, when i left for kuala lumpur for 1 week they asked me to resubmit a tm30 even though nothing had changed apart from exiting/ re entering thailand. Just my experience no doubt someone will have a different experience.
Never done Patongs immigration but I do Phukets quite often and they are excellent, I do occasionally get a remark about LFC as I too am from Liverpool. But yeah as someone who has been to immigration around most of Thailand I find Phuket to be the most pleasant. Please keep it like that.