First of all, big thanks to Vlad for creating this fantastic mod. It's by far the best one I've tried; dialogue, story and action are all superior to anything else IMHO. Loved the Severed Hand and the dream/hallucination thing while leaving Kuldahar in particular. GREAT job!

Now to the point: Is Dorn's Deep and Wyrm's Tooth available in NeJ v4.2b, with the NeJ2 v6.02 patch installed? If not, is there any way to upgrade my version without having to start a new game? I'm currently at the end of the severed hand and Larrel simply won't let me leave for Dorn's Deep...

You are done for that version. If you are playing a BP or Big World style installation, there is no way to upgrade to the full NeJ2 691 version as that is not compatible with what you are playing. Once you go to BG2 again, you still have Halruaa and saving Ulcaster so keep Hrothgar in your party in early parts of BG2.

Hm... Ok. Oh well, I'øø just have to live with it I guess... play through at some point when I don't need any other mods... about part 2, It's now 10 days since I got out of Irenicus' dungeon and Hrothgar still hasn't asked me to go to Ulcaster. He's said something about having to think about something, and since then he hasn't said anything... is this how it's supposed to be, or is my version bugged?

it won't happen right away. You are on the right track when he is thinking of something and there should be another dialog soon about the quest. That version should be fine for Hroth to give the Halruaa quest. It happens within 14 days of exiting Irenicus' abode.
Good luck!