Yes you have to report if you stay IN Thailand 90 days if you not then not report it. If you live in Bangkok not report it as well, if you stay first night hotel let them report it
You can get a multiple 90 days and a 60 days after that. There is no limit to 90 days one time as far as I know I did my multiple o in Sweden and Penang
Yes I can show you the stamp i got in my passport she did it twice i was not there any of the time. Second time the immigration gave me 7 days since i have a child otherwise they said get out now.