In morrowind what is the best heavy armor and bow and arrow. (and were to find it)

The best set of heavy armor is Daedric, which is scattered all over the game world. Here is a link of where to find all the pieces:
Daedric Items

There are also some unique artifacts that are slightly better than Daedric Armor, such as the Lord's Mail, found on an NPC in the tunnels under Ebonheart. Then there is the Helm of Oreyn Bearclaw, gotten by doing Malacath's Daedric quest. There are also the Fists of Randagulf (left and right gauntlets), found under a loot trough in Illunibi.

As for the best arrows, those would be the Ebony Arrows of Slaying found in the hollow tree stump behind Thirsk in Solstheim. However, there are only 5 of them.

And finally, for the best bow, I believe that's Auriel's Bow, found on Ralyn Omavel in Ghostgate, Tower of Dawn.

I hope that info helps.

Can you pickpocket therana after you give her the bow ?

I don't know, but there's no harm in killing her for it if you need to. There's a Morag Tong bounty on her, anyway.

That's even worse ! If I kill her now : I won't get the writ which I badly need . I won't be able to become the head of the Telvanni Archmagister . Those 2 things are bad enough .

If you want to complete the main quest the legitimate way, however, you need her vote for Hortator.

I've already finished the main quest .

I believe you can still kill her. The Telvanni are cool like that. I think you could pretty much kill everyone but Master Aryon and still get the Telvanni Hortator vote.

But then the Morag Tong posese a problem.

No it doesn't.... why do you think that?

Dude , I can't commit difficult crimes legitemately without using the writss.... What I'm tryin to say is , let's say I'm going to kill a gaurd infront of another one , well , I
Wipe out a whole town , but then I show a writ too a gaurd and then they don't give a damn after that .

Maybe I'm not getting your grammar, but I still don't see the problem.

Simplified:commit any amount of crimes without talking to a guard , when your crime spree is over , then just simply talk to a guard and present the writ and Walahhh! you have now just cleared your bounty.

Ooh... that's cool. I didn't know about that. I still don't see why it's a problem though... maybe I'm just slow.

If those 5 arrows dont last you for the rest of the game, then try doing the side quest where that one Rich lady goes insane and has those Dwemer things that shock the shit out of you... i dont remeber the quest name. But do that quest and when you Kill her DONT dispose of the body. keep clicking her corpse and there will be 50 more arrows in her.