In chapter 2 when you do the quest for 10 000 gp is that the troll quest where you have to kill all the trolls?
and after you kill them the guy De'arnise is dead, so do you actually get the 10 000 gp??
Also should i replace some one for De'arnise's daughter or should i let her wait in the copper cornot?

she doesn't have to be in your party. She should be outside in the small fortress in the SW corner of map screen. Talk to her

No, pick her up and do the quest with her or you won't get but 500 gp if you do it without her.

Actually, the 10,000 gp quest that you get in the Copper Coronet is the Firkraag quest. But, if Nalia is in your party when you do that quest, you will get 10,000+ gp.

Nalia gives you her quest in the Copper Coronet as well.