Hi Ben!
Welcome to the forum and enjoy your precious!
I have the same model and my first advice to anyone who buys one is to check the relay panel. Most of this models i've seen had 99% of the problems from that, to be more precise it might have some water in it and that will give you many errors and you'll end up changing parts that dont need to be changed. The dipstick problem: it's not really a vacuum issue, as much is a spilling issue; mine had some sort of "home craft" made by its former owner and during long trips it was spitting oil, but its like 5 pounds for the salvage yard and you wont have this issue again (i dont know for sure, but I think you can take one from a passat B 5.5 or Skoda Octavia, but again I am not 100% sure). I also bought a gorgeous black leather interior with door panels, all in very good condition, from a scrap yard for 80 quid lol (see picture :D)
Your plans sound good so far, we are waiting pictures to see the progress!!
Fingers crossed with the MOT and happy motoring!!!