Nope. I don't really know what it's about. It just sounded boring. Is it pretty good?
Of note, the Deathbrand quest in Solstheim doesn't even start until you're at least LV40, soooo
Oh, http://uesp.net/wiki/Dragonborn:Deathbrand_(quest). I rounded it in my head. >x<;;
I dunno, it literally says "You must be at least LV36 to do this quest". *shrug* Probably the same kind of thing that happens when you visit, say, http://cloud-2.steampowered.com/ugc/919013985446221312/915D7B6092A87684782E8931884DE904E0E62F86/ - nothing there.
Yes. Again, much like how I can discover and waltz into Wolfskull Cave before starting The Man Who Cried Wolf, you can certainly find the book (it's everywhere in Solstheim) and Haknir's Shoal before being LV36 and starting the Deathbrand quest.
I use the SkyUI mod, since I can't stand the vanilla UI and I like seeing active effects. It needs SKSE to run, though.