Just 3 Questions left.

1. Should I sleep with Jaheria or talk with her?
2. How do I get Jaheria's Harper pin? I am at the end of the romance stuff and done the quest stuff how long till I get it?
3. If I sleep with Jaheria how will it affect my relationship in Throne of Bhaal?

I'm pretty sure you can sleep with Jaheira without any negative repercussions in ToB. the only person i know of that you shouldn't sleep with in Shadows is Aerie...

as for the harper pin, you need to do jaheira's curse quest, and then her harper quest. eventually, you will run into elminster who gives Jaheira the harper pin.

I done both the quests already, I cured the curse and I had to kill her old tutor cos he attacked me. After I slept with Jaheria I walked from location to location but never met Elminster.

HELP!

You most likely have the 'Jaheira romance bug'. Try searching for patches on the net (I know there are a few out there for this problem). It's bloody annoying I know, just as things get interesting the romance is brought to a screeching halt. I hear if you fiddle around with Shadow Keeper and change her romance dialogue number to one less than it currently is then it fixes the problem as well. It's ultimately your choice on whether you want to fiddle around with the game like that though.

also, if you already slept with her, try staying in some wilderness area and simply pause your game and let it run for about an hour, then unpause. Elminster might appear.