i wouldn't buy a diesel, any brand, that had to have it's entire fuel system replaced. There was a reason for that and it sounds like something bad on the prior owner. The dual mass flywheel is a known issue on the previous gen but shouldn't I wouldn't expect it there on this gen. Might check, but i don't know if the timing belt was done too soon. Passat we took in for a family member was told to wait till 130k. the older 1.9 was at 90k. Too many main problems on major components to consider in my book. they all show bad maintenance on the previous owner's part implying further problems to come.
In our exp, VW are extremely exp to repair, even if you do the work yourself. Parts aren't readily available and if you can't do the work, finding someone who can is even more expensive. Basic Maint is the same way. in our family ownership includes:
06 tdi jetta - egr blew twice, dsg was failing, dual mass flywheel failed, a/c pressure switch failed, headliner issues, sun roof issues, turbo vane issues
06 tdi jetta - dual mass flywheel failed @ 80k- traded it off
09 tdi jetta - was ok but totaled.
15 tdi bug - ok so far but never driven.
15 tdi passat - ok so far but never driven. general maint very high. dsg service was 250-350$ last week. can't do at home without vw software and special tools.