With regards to DPFs, they will eventually clog up. It's a filter, and is classed as a consumable, but it should be lasting to at least around the 120,000 mile mark (at which point VW say start checking it every 10,000 miles). Obviously when the soot is burnt off, it still leaves ash behind, and you can actually check your oil ash content with VCDS.
I believe quite a few people have had success with a hose/pressure washer though.