Priest and warrior combo..

So I am doing a priest and warrior right now since they are 66/67.

However, I was wandering when I reach 70, you think it would be easy to do groups and such? Priest is holy and warrior will be protection of course. I am not talking about doing heroics but looking to get the kara key quest done at once. So my question is should I make my priest my main control and warrior on second control? Or should I make warrior main and my priest and spec him shadow. Just trying to find a way that I can tank and keep my group healed. But I think this might be too risky.

Just to keep my sanity, I either multibox instances by myself or limit myself to DPS support roles if I group multiples with other people. And even then it is almost exclusively with my guild which consists solely of real life friends. On the rare occasion I do a PUG I only take just one character. Too much drama and misunderstanding can occur otherwise.

It would be way too much for me to try to take on both primary roles of tanking and healing ... unless its an overpowered situation, like 70's in Scarlet, then it doesn't matter.

Most likely I will spec shadow anyhow. I will prolly be running with my guild anyhow.

But still overall, a shadow priest needs to assist for the most part. Shackle can be done easy.

Just need a a good healer.