i have a question, i did some side quests, but now i've gone on with the game and i just arrived at the underdark. will there be a time that i can go do the rest of the side missions? or is the game gonna end eventually and i won't get the chance to have more fun?

YES! i'm a dungeonmaster!!!! alright!!! i mean... splendid... so anyway.... yeah.. answer the question please. thankyou!

I assume you mean the various quests in Chapter 2. Well, yes you will be able to head back to Athkatla later.

Hehehe... Before ya know it you'll be Magister.. Then you'll be a Zhentarim Guard! Grrr! Die die die! Foul Zhentarim! Die! Die! Die! ::cough cough:: Right... What were we saying? Ah yes..

You can do all the sidequests later... except for the City of Caverns, Brynnlaw, the puzzles beneath the Asylum, and the few sidequests in the drow city.

what do you become after a elite waterdeep guard and how many posts do i need??

U turn into the "Dungeon Master", I think u need to 49 posts.