Should smoke alarms be on AFCI circuit?
You can have them on an AFCI circuit if you like. Newer codes would require it, but if they are not on an AFCI now you do not need to add one just because you are moving the circuit the generator panel.

No, newer "combination AFCI" breaker are NOT combination AFCI/GFCI breakers. It means they detect parallel and series arc faults.