Under Healing, it says that First Aid can be used every encounter or scene. It then says that Medicine can't be used in combat, but suggests that it can be used other than to assist Resilience or Long Term Care. If so, how often can it be used? Is it the same as First Aid (except not in combat) or something else?

istm that it's something that might give Fortune to the daily Rest and Recovery Resilience check (p.64)

Medicine can be subbed in for "Immediate Care" in place of First Aid, and usually should be (if available) because it is safer. However, if the attempt is successful it counts as a successful First Aid check for the Act (in a structured encounter) or scene (outside of one).

Medicine is also a knowledge skill, and so could be used for certain types of forensic investigation, identifying the contents of a pharmacopoeia, et cetera .

Medicine can't be used in combat because there's just not enough time for proper medical attention during a fight. After the combat is over however, the medicine check can be used instead of first aid to get someone back on their feet and able to get back to a place of safety where rest & recovery can occur.

Cheers. That's what I expected.