You need to do the 90 days reports. The hotel is responsible to file a tm.30 within 24 hrs after check-in. Most hotels do that online. Just make shure the hotel makes a tm.30 and ask for a copy/screen shot before you go for the 90 days report.
you can get a retirement visa from the embassy in your home country or alternatively you can get one at the immigration office when you're in Thailand.
Having a second option is a good idea anyway. I heard of blocked Wise and N26 accounts. If that happens you're happy to have a second option to transfer money. It never happened to me though.
I thought the same. It's worth considering as an alternative option. The downside might be that it's more difficult to open bank accounts as it's considered a tourist visa.
note that opening a foreign currency account needs some time. I had to wait three weeks for the bank book of my foreign currency account at bangkok bank.