That drain clogging up is a common problem.
Try a coat hanger wire, or a piece of twisted strand, or woven strand flexible steel wire & twist/rotate it as you insert it into the rubber drain hose where it exits the firewall. Don't get crazy & poke or twist too hard, so as not to damage the drain hose, or its seal at the condensate box. Then run the ac & see if it'll drip out the drain.

Guitar string works pretty good for that. Maybe a low "E". Poor man's snake.

What about the wiper arm penetration?

Temp tape the windshield trim see if water leak stops.
Mostly if leak is above rear view mirror area of headliner.
Been told by glass shops the windshield cab seam rusts out.
Have not figured out the floor leak..can see a trail made over the years..

Amazingly it has stopped. The only thing I did was reglue the door weatherstripping that was lifting a little bit. Hopefully it will stay dry.