Your full time job is likely your occupation so you can indicate accordingly.

Yes you may indicate N/A by hand where indicated.

Best to work with an attorney for submission of the request for evidence.

No but you can inform the officer at time of interview.

Yes you may be able to as an adult USC child but more information is needed to determine next steps.

Yes the photos with passport stamps should suffice as proof of meeting.

You may be able to travel while the U visa is pending but more information is needed about your case.

Best to have an attorney review your case to determine if CSPA would apply.

Yes such a request should be accepted.

Refer to the direct filing addresses on the USCIS webpage.