Welcome to the forum.
1. Personal choice...irrelevant to immigration.
2. There is no 90 rule. You can marry and start the process for concurrent I-130, I-485, I-131, I-765 filing right away after obtaining a marriage certificate.
3. No. No.
Married or not, once your I-94 expires, you will be out of status and deportable until you file a proper I-485. Then, you will be granted authorized stay in the US unril the I-485 is either approved or denied. Be aware that you cannot work (in any form) or leave the US for 3-6 months after filing the I-485. Good luck.