When do I file the DS-160?

Later in the process, after approval of FORM I-129F with USCIS, and after USCIS moves the case to the National Visa Center.

Would an arrest affect me getting an immigrant visa?

This particular arrest will most likely not negatively affect your application for an immigrant visa.

Will I be able to come back?

You may have issues re-entering on an F-1 visa while being married to a U.S. citizen. Your status will not change unless you file for a change,...

What?

It should work if our cousin has sufficient income and is a permanent resident or a U.S. citizen. Form I-864 in addition to the Form I-864 of the...

Can my parents come to USA on travel visa and then submit and adjustment of status for them?

Your parents should not enter on a B2 visa with an intent to adjust status.

Can immigration find out my background, even if its not showing in my public records?

Carefully review what is required of you and always answer truthfully. If you are asked if you have ever been charged with a crime you must answer...

Is it possible to begin working on an H1B visa one month before the "start date" selected by employer-sponsor on LCA/I-129?

No, in the situation as you describe it, you cannot start earlier.

My I-130 case approved but I-485 still interview is scheduled. Please can you explain what is it mean?

It is difficult to understand your question, please provide more detail. It is likely that you will be asked to attend an interview at the end of...

You will likely be questioned because, especially since selling is involved, it appears that the described activities fall outside those permitted...

What can I do in this situation?

There are a lot of issues involved in your question: where your mother should await her green card, the time it will take, travel options, intent...