Tell me more about this Paths of the Damned. How many books are in it? And what kind of time span are we talking about? Assume an average 4 hour session, how many months of play?
3 books, but they're often somewhat hard to find and/or expensive. I don't know if there are any PDFs of them available, either.
They are:
Ashes of Middenheim
Spires of Altdorf
Forges of Nuln
All 3 are fairly short, and you might wonder why the heck they're hardcover. I know I did!

They have a sourcebook for their respective city in the first half, and the module in the second half... It's a good way to do things, since you can get a great feel for the adventure setting and throw in things like clawed daemons hanging from Middenheim, and troops of dwarves working to repair the eastern causeway.
I really couldn't pinpoint how long each one would take... It's very much dependent on your players. We got the prelude from the core book and Ashes of Middenheim done over the course of maybe 12 sessions - but we screw around a lot and have short sessions, so YMMV. (The deadliest character, by the way, was the freaking halfling fieldwarden. Slings are insane in WFRP2.
Eyeballing Spires of Altdorf, it could be a very short or very long adventure, depending on how perceptive your players are, how much you want to drag it out, and how you pace the events.
I have quite literally never opened my copy of Forges of Nuln.
-O