Yes. You should think about doing that. An apartment or a condo in your own name gives you something to call your own. And puts you on the map. For a visa think about student or retirement options. No reason to get married for the visa. Good luck!
Yes, but you have to think, for a little moment, how those people would help you out, if you had nothing, and needed support, and I guess they wouldn't be so quick to change their marriage status to help you. So give generously, but make sure you have your eyes wide open.
In my experience, once I left the country I did not need the 90 day report slip anymore. As the clock is set back once you enter the country. In fact I've missed a 90 day reporting and left the country and returned with no slip and had no problems returning to the 90 day reporting once the new entry stamp has been activated.