For point 1 it is another "Depends on the Office" question about redoing TM30 when returning to same address from overseas trip. Jomtien there was no need. Chiang Mai must do.
Anonymous participant Worry about that if it happens. Currently there are no issues and nobody can predict the future. Enjoy the visa as it is now. If anything changes deal with it then.
I think it is rare for anyone to be fully denied entry in your situation. Guys I know been doing one month on and off while working FIFO were told get a visa but still let in. If you want to feel safer apply for a Tourist Visa. As for condo rental it does not matter what visa you are on. I have done it on Visa Exempt. Pretty much standard is 1 month rent in advance and 2 months deposit
Multi-Re-entry permit is 3800 and aligns with your visa. Most visas are 1 year so for 5 years the cost is 19k. Do you really not know the basics about visas in Thailand?