Upgrading from 100 ton to 200 or 500 ton question

See 46 CFR 11.201(j)(1):
j) Professional examination. (1) When the Coast Guard finds the applicant’s experience and training to be satisfactory, and the applicant is eligible in all other respects, the Coast Guard will authorize examination… [emphasis added]

This means you can’t sit for the exam until you meet all the course and se a time requirements.

If you were to apply for Master 200, you will still need to show sea service on appropriate tonnage vessels, and there would be at least a limited exam that covers the things that are tested for Master 200 and not for Master 100.

You should not need “advanced” first aid. For a national endorsement (license) without STCW, it’s a one time requirement for first aid (basic) and CPR, so if you have Master 100, you don’t need to re-take this.