Hi, if you need the car fixed quickly then let the mechanic fix it otherwise as you are going to have to repair in the long run don't bother. Personally I would have my own gearbox repaired as you end up with a known quantity you don't know what you are getting with a second hand item.
Hi I obviously did not word that too well what i meant was as soon as the engine is warm enough not to need the choke if you stop the engine and restart does it run normally. The engine should be up to temp long before 20 mins.
I think the pipe you are asking about was fitted by vw years ago on a vehicle recall. The reason for it was that the heater matrix was prone to failing and hot water entered the footwell. There is a fix by fitting a mk3 matrix which is a direct replacement. Alternately just remove it and either fill the gap with a piece of pipe or replace the pipes altogether. On rereading it i note you have replaced the matrix so i would just remove the valve and either bodge the joint or replace the heater pipes.
