Hi Dan! As far as your first question goes, “Clearance on request” means the controller has acknowledged your request for clearance, but cannot immediately provide it to you because he/she is dealing with higher priority issues at the moment. They will get back to you as soon as they can. If you have been waiting for 10 minutes or so, you may need to request clearance again as they may have forgotten you.
For your second question, if VMC, do just like you said. Treat the situation as if you either canceled IFR in the air and are now VFR -or- as if you were cleared for a visual approach. If IMC, you would have to pick an approach and fly it. In real world there would be separation because once the controller realizes comms were lost, he/she will clear the area. When I file IFR real world, I like to make my last point in the flight plan an IF/IAF for a given approach into the field. That way, the controller knows where I am going if comms are lost.
Hope this helps,
Matt