Your parents may stay beyond their authorized stay if their AOS application is pending.

Speak to Canadian attorney(s) about the penalties for using fraudulent names in Canada.

The forms you would file are 1130 and I485.

USCIS ASC officials will notify you about biometrics examination problems/issues and reschedule another appointment accordingly. Otherwise, you are...

It is possible to obtain AP as a DACA recipient. Check for specific requirements.

Your question is unclear. Show an immigration lawyer the denial letter. The lawyer would discuss your viable options.

No. A B1B2 purchase of property would not help in obtaining US permanent residency.

A USC may petition for a stepdaughter under 21 and unmarried, at time of marriage to FN spouse. There is no visa category for stepparents.

A person may file the I765 and I131 with applicable filing fees. The fee schedule and calculator are available on USCIS website.

You must appear for as many interviews as scheduled. Failure to appear would risk the denial of I485.