Get one from the Social Security Administration.

I believe you will get a receipt notice once the application is filed online and you can use that receipt for the I-485.

It would make more sense to bring the medical with you to the interview.

Yes, a person who entered the U.S. without inspection is subject to the unlawful presence bars to admission.

Perhaps the local office will also adjudicate the I-360.

Your I-751 receipt does allow you to work, but if no employer wants to hire you, then there is little you can do. Similarly, the I751 receipt...

You have a permanent bar to admission, but you could always apply for a nonimmigrant visa waiver.

If you move to another USCIS district, it could be an issue. But within the same district it should not be an issue. The N-400 form instructions...

Yes you can file for removal of condition even if you lost your condition permanent resident card. You may wish to apply for a replacement card also.

File it in the state where USCIS is processing the application. Normally for an I-485 it is where you live.