Yea, the drain is that large oval black ring just under the filter housing, it will look clear until you put your fingers down it. The filter is held in place by 2 white plastic flat clips that you can see in both top corners of the filter. Just hook your fingers on the inside edge of the clips and they should pop open, tip the top of the filter forward and it will lift out.
The water drops into the main fan unit for the heating and comes out the bottom, I think through the foot vents. This can corrode the spindle and put it under too much load, hence the resistor blowing.
The sunroof that si.c1978 mentioned isnt as daft as it may sound although sunroofs are very rare in the Vec C, all sunroofs seam to suffer from the same problem if the drainage channels are blocked, ive had a few cars over the years where this has happened.
There is no fix for the pollen filter problem except keeping it clear. The only mention in TIS is to drill a hole in the bottom of the fan housing, but thats no fix, that just stops a pool of water settling in the bottom of the housing.