hiroin

It would be highly unusual for a couple that entered on a K-1 and got married within the 90-day time frame to get denied. You certainly won't be denied for any of the reasons you mentioned. You got married in a courthouse, and it's a legal marriage and you have a marriage certificate, so you fulfilled the requirements of the K-1.
Your marriage certificate is the one document that will allow you to change your name.
It's quite normal that a couple that just moved in together doesn't have a truckload of evidence yet.
Don't worry too much; if your marriage is genuine, then no I.O. will hold it against you that you are on a super-tight budget right now.
Relax.

Yes, a simple "A" indicates Alien; a small X before that (x-A) indicates that's an extraterrestrial alien.
For example, Superman was an extraterrestrial alien. He had no legal basis to adjust status and was actually guilty of false claim of U.S. citizenship by pretending to be Clark Kent. He used false documents in order to secure employment at the Daily Planet and his adoption was fraudulent from the get-go as well, which consequently means that all of the Kent clan should have been in jail for many years, and Superman should have been deported with a lifetime bar attached.
Strangely, Americans have different standards of right and wrong when it comes to their heroes.