Yes, you can put fast cure over slow or vice versa.

As for the other question, prepare for a great debate. I think that was what got the Hatfields and McCoys started feuding. I prefer to roll on epoxy to fresh cloth (first coat) and then squeegee the fill coat. Rolling on gives me more control to put only enough resin to wet out the cloth, and I find less chance of the cloth floating. Squeegeeing the fill coat leaves a smooth finish with less sanding.