Yes you should submit an AR 11 even as LPR.

You should contact a divorce attorney for further guidance.

Yes you may do so with a valid reentry permit.

You can request a changed location for interview by reaching out to consulate directly.

The I539A will also be considered withdrawn.

Yes you may file the I485 is otherwise eligible.

The I485 will require the I864 affidavit of support from the petitioner.

Wait for final decision and have an attorney review your case for guidance.

This can happen as each case is filed separately.

The previously filed AR11 should be sufficient.