RE: Archer or 421c
Hmmmm.... Couldn't answer that one for you. All I know is that an FCC license used to be a required document for the plane, but not anymore. It is required if you'll be flying international, though. As for the other question, you can use the mike all you want without any kind of license. I think it's because the FCC has designated those frequencies for aviation use, so the FAA regulates it. I could be wrong, though.
PPL in Training
Commercial Pilot ASEL - Instrument Rated
Air Traffic Controller - Anchorage