What ever you want to provide as proof, your home country embassy has affidavits they can sign for you. But for freelance work what would you show id you were a writer, painter, web designer, etc
No need for grab car at suvambi,, there's a whole row of taxis waiting for you. Check what you should be paying in the grab app and use that to make an offer to the taxi driver
You will need to get her a dependant visa, renewable each year. The company should help you with this, otherwise you will need to visit immigration or find an agent.
If you act like a tourist and visit other countries for 3 to 5 days minimum you can come and go as you please on visa exception. If you leave for an hour and fly back you may be questioned as your not allowed to live here year round on visa exception .
if you return on the same day you are trying to live here on a tourist visa and they will take you to a room and question you about that. If your passport is full of Thailand tourist visa & visa exception stamps they may deny entry.