It's confusing.
Is it just me or there is no content for Tob part entirely?
I failed to find even epilogues for NEJ's npcs. Please, tell me I'm drunk and am imagining stupid things

Nope your not confused, etc. There is no content at the moment for TOB.

Damn... Well, at least i won't have hard feelings about replacing Hrothgar with Sarevok. Little compensation, though it's better than nothing.

One more question then - have NEJ's npcs got any talks in Soa part? As I know there are their quests, banters, Leina's romance. Anything else, like interjections?

I would say not as much as you would like. Leina is the only one that has alot at the moment. So after Halrurra don't feel bad if you want to exchange them out for a totally different group.

I've finished Halruaa. I don't want to take npc's (Melora, Taffic, Sharteel, Dar) quests in my current game - I'd rather to postpone them for the next runthrough (hopefully some new content will be released that time). For now I'm interested only in Hrothgar's quest - the 'explanation' he has given after arriving from Halruaa suggests yet more plot to be uncovered. Is there any of it to be found in the current version or I can sleep peacefully and not worry I'll miss anything important?

Fear not and have a peaceful rest. Until the next addition you will miss nothing by removing Hrothgar from your party. You have completed everything at the moment he is tied to.