Taking on water in the interior

Yes, yes and yes. You may have water coming in thru a rust hole in the sub-cowl area, but it is more likely that you just need new seals at the wiper posts. The kits cost about $25 and can be installed with minimal skills by following the instructions.

As for windshield gasket leaks, yes rust can lift the gasket enough to let water thru. I recommend that after replacing the wiper post seals, testing with a garden hose to see if water is still coming in. If so, then try to determine if it's low (from the sub-cowl) or higher up by progressively raising the running hose from the cowl vent (check for leaks before raising the stream to the windshield). Then if you need to pull the windshield, make sure you hit all the wire wheeled rust with something like POR15 before reinstalling the glass. Good luck!