I've already decided on making a dwarven fighter/cleric who has high constitution of 19, high strength and 17 dexterity. He will be main combatant.

For the 2nd combatant- I made a cleric/thief in Baldurs Gate 2 Enhanced Edtion and that made the game too easy. Can I make an elven cleric with high dexterity so he gains bonus AC when draw upon might or does that work?

I soloed IWD 1 with a ranger but never touched the expansion because I heard a dragons involved and thats a bit too extreme to solo for me :)

My goal is that the fighter/cleric I keep but I want some kind of thief cleric that can fight. Is it at all feasible to take a thief to 2 or 3 and then dual class to cleric right away for backstab/SATTACK and occasional stealth benefits. Sometimes stealth is useful.

Should I go cleric 2 or 3 and then thief or opposite.

Assuming IWD1, there will be no advantage to AC from 19 DEX -- that will only get you a boost to ranged THAC0, reaction adjustment and thieving skills. So no, there is little point to making an Elven cleric other than role playing purposes.

If you want a fighting thief, you really should go for... a fighter/thief multi class -- you seem to be favouring clerics over all else, and this will restrict your weapon usage a lot.

What would be the purpose of stopping at 2 or 3 Cleric levels? You get basically zero benefits. Same with Thief. 2 or 3 levels isn't enough to pump the Thief skills far enough to be useful throughout the game. Why not go for a FTR/Thief, as Hickory suggested or, if you're set on a Cleric/Thief combo, then go for a multiclass.

I'd highly recommend having a mage of some flavor in the party though.

Well I just wanted to try something different and I like the cleric class. An Elven Cleric would be fun so long as the party can get through the game.

If that party cant do then I might as well solo.

An all cleric (multi) party? Hmm, there's a roll play in there somewhere...

Anyhow, putting that aside, if you want something different, and you want a cleric/thief, why not go for a Gnome? Ok, they take a hit to WIS, but you don't need maximum WIS. They have juicy CON based bonuses to their saving throws, and also nice thieving bonuses.

Then again, if you want an Elven cleric, I say go for it. Let's face it, if you can go through solo, you can go through with an all cleric party, and an Elven cleric has a place in there, right?

Thanks for your tips. I will go with the gnome like you said.