I've done each one once but the A2 is due for a cambelt change later this year, so will probably be done again. Three of the bolts are specials with rolled-on stepped washers, so difficult to replace. You may find some kits somewhere. There are no gaskets to replace apart from the one on the oil return flange, which you can buy from Audi.
I didn't say there's no need to remove any hoses, only that the coolant hoses to the EGR cooler don't need to be removed. Otherwise all the hoses connected to the turbo have to be removed, of course.
I haven't noticed much difference in performance (there's not much performance with a 1.2 anyway!). It will affect economy though. But if you leave it too long (and it needs doing), the VNT will jam or it will keep going into limp mode.
RAB