They do a 6mm rubber edge seal that might be small enough. Otherwise give them a call, they may be able to source something that isnt listed on their site.
As for the rear drain holes. They exist at the rear corners, coming inside to behind the roof lining, where a plastic pipe is attached which leads away to the rear arches. Unless you want to pull the roof lining down you may be best trying to "rod" the pipes from the rear arches. I need to get mk mk2 into the garage this evening, if I remember I shall try to get photos of where they come out for you.
