If you manage to fit it, but have to remove the standard ducts, you will have to make some or it will be less efficient than the standard ic.
That was the mistake a lot of people made when fitting them to the Mk4, they just stuck the ic on the with no ducting, so all the cold air would just fly...
I've now seen and heard a lot of good reviews about the wings from them, so I'm going to give them a go once the last frost has passed. I didn't have any wing rot until some kind soul decided to drive into my car in a car park and crumple my wing. The other side just has stone chips on the front...
It sounds like it could be the common issue of the wires going into the door inside the rubber boot being cracked/snapped.
They control the interior lights when opening that door, central locking from the key (possibly the remote being the main door), electric window, and the speakers in that door.
Mine just came up on the code input screen when I turned on for the first time after installation.
If it is the same as mine (pictured below) I will get the manual out and have a look for you.
You don't need to change the ash tray though.
You have to cut two bits of the centre console away behind where the climatronic sits. This is because of the slight difference in shape of the cages, you can't see it once the climatronic is fitted though.