BuGGaTon: Oh, they can, trust me. The game doesn't go into much detail on the precise nature of the attack (all I know is that the ghosts like to "batter" my dwarves), but in my experience the end result tends to be a severed limb or a ruptured internal organ, if not instant death. It's all kinds of Fun.
To people who offered congratulations: Thanks! The mighty fortress of Wipemine hasn't lived up to its name
quite yet. I now have a small but bustling population of 8 dwarves, and while they're currently locked indoors on account of the latest siege, I have at least finally produced a comfortable surplus of coffins. I am now working on a long, narrow, twisty passageway lined with cage traps, to lure the enemy into when the time is right. It will surely bring either Victory or Fun!
Memorials are definitely the way to go when it comes to vengeful spirits. There were two ghosts whose bodies I couldn't recover because they were outside with all the goblins, but memorializing them did the trick quite nicely.
Triaxx2: That sounds really useful, but I think that only works for jobs queued by the manager (via j-m-q)? Pulling a lever only shows up on the (j)obs menu, and regrettably I can't seem to find any way to prioritize the tasks in that list.
Speaking of which, I have a bit of a labor-related problem. My chief medical dwarf was imprisoned for missing a production order (Moose hoof items? Seriously?), and is chained up in prison. I got worried when she started to starve and get dehydrated, and so I disabled all of my engraver's labors except for "Feed Patients/Prisoners". However, my engraver now just alternates between "No Job" and non-toggle-able activities like harvesting plants and drinking. Is there something I'm doing wrong? (Some people elsewhere on the forums suggest turning the prison into a five-star luxury hotel with booze stockpiles and ruby-encrusted masterwork beds, but come on... this is a prison sentence, not a vacation! These guys need to pay for their completely unavoidable crimes of omission! What's the point of having a demanding and capricious ruling class otherwise?)