Fire is fine, but if you are lvling (lvl 20) then you would benifit from Frost. People will tell you all different things, but Frost is the best spec to level with. You get way more control.
Once you hit level Cap (You will never hit Level cap at the current content cap - you will be 85) you can really solo as any spec because you'll be so much stronger, but when you are running around in the 20, 30, etc. areas - you'll have more luck as frost.
Having said that - you can absoluely raid, solo, PVP, etc as Fire...
Most things you worry about never happen anyway.