If you leave every <89 days for the next 5 years you never have to do a 90 day report
If you stay >90+ days yes you have to do a 90 report (you have 2 weeks prior and 7 days after your 90 day Date)
Yes every time you return from an international trip you have to do an in person 90 day report (TM47) at your local immigration office
Your second 90 day Report TM47 can be done online as long as you haven’t changed passport numbers or immigration offices
You will need to have your landlord or hotel do a TM30 within 7 days of you returning to Thailand in person at the immigration office or within 24 hours online
…if you have a cool landlord/Tambien Bahn housemaster you can get their information and do it online not bothering them all the time you have 24 hours to do this
The landlord or Tambien Bahn housemaster can also do the TM30 via snail mail
Some condo buildings do the TM30 at the front desk
You can’t do a 90 day report TM47 without the TM30 it’s a ฿1,600 baht fine in Bangkok not sure what it is in other immigration offices
For the TM30 in Bangkok if you take short trips in Thailand (weekend to Pattaya as an example) you don’t have to register once you return to your condo in Bangkok