[SixOfSpades]

If a party member wants you do do something (such as Korgan wanting to recover the Book of Kaza) as a condition of joining your party, it's best to get that done fairly soon (within 2 days, I'd say), or they'll leave. Don't worry, they'll give you a warning ("Hey! I thought you said we were gonna go do this!") in time for you to do their quest & keep them happy.

If you're bogged down with quests already & don't have time for another one, don't take that NPC into your party yet. For instance, if you tell Nalia to go ahead to her keep and you'll meet her there later, she'll stick around until Doomsday waiting for you, and so will the quest.

As has been said before, the quest that starts with Renfeld the Poisoned Man does have a timer--if you don't get him to help soon, he'll die. Interestingly enough, a similar quest (you happen upon a man buried alive) has NO timer--you can leave him locked in a coffin in a half-filled grave for a MONTH & he'll still be alive and well when you get back.

You mentioned the woman who wants you to meet someone in the graveyard? That quest DOES have a timer--I think you have 3 days to make it to the meeting, or the offer will be withdrawn. But it sounds like you've already talked with the person.