You can unclog those drains pretty easily. If you open up the trunk and remove the trunk interior side trim panels (remove all the little quarter twist plastic attachment screws) you will see fairly large diameter black rubber tubing running down from the drains. Carefully pull the tubing out of the hole that exists the trunk bottom and pull the top end off the drain fitting under the trunk edge channel. You can then unclog this tubing with an unbended coat hanger (or something similar) and some high pressure water from a garden hose. Mine were all clogged up with pine needles and dirt and a huge plug of gunk came out with the water. I did both of them when I replaced my antenna mast.

As for the sunroof, mine has been problem free. I try to keep the interior area free of pine needles and other large pieces of junk. When the roof is open I stick my shop vac's narrow nozzle down in the channels and suck this type of stuff out. I also try to keep the tracks lubed with some WD-40 but getting a heavier lube in there seems difficult without making a mess. If someone has some better ideas I'd like to hear it. I'm always paranoid the thing is going to jam halfway or completely open so some preventative maintenance would be a good idea.

Scott