#4 drain hole -heater and a/c drain...
 

Do I need to remove the plastic panel to the left of the battery(Looking to rear of car)
to access the drain hole? If so what kind of torx wrench/bit would I need to remove this panel?

My gas filler/drain hole is plugged for sure. I will have to get a bike brake cable to clean out the holes. Nothing else works . I have referred to the previous thread on drain hole cleaning. I have a 2001 Boxster base. Thanx in advance.:)

The front drain holes near the battery are exposed, don't need to remove anything.

Take a look at the shape of the bottom of the #4 drain and consider if you want to poke something solid down it. Maybe soak in dishwasher detergent overnight and use compressed air or water pressure?

Diagram

Mike has a very valid point; many of the drains in these cars bend around other things, so trying to push a wire or something similar through them ends up with a puncture at a bend, and a leak in a very difficult to access area. Something that will soften and lubricate the plug followed by air pressure (just don't go nuts here, the drains are thin walled rubber hose) will usually dislodge a blockage.