I bought Rage - Anarchy Edition, and I've only played up to where I've gotten the sniper rifle, but up to this, I don't have the armor, just the Fists of Rage and the shotgun. ( I'm not sure if I have the buggy. )

Do I have to reach a certain point for the armor or should I have gotten it right away?

Yes it will come soon. Its integrated into the story. You'll see it soon.

How many "sewer" mssions are there? I found one near the very start of the game but I take it there spread out thouout the game?

thanks in advance

http://rage.wikia.com/wiki/Sewers

I have the same question. I got Anarchy Edition and beat the game. I Dont have the armor at all yet.

At first you don't have the choice to change armour, but later on in the story you're told to change it. When that happens it will give you 4 options of different outfits, each one with a different bonus. The 4th one on the far right is the Crimson Elite armour. It's hard to give you more specific directions without using even the smallest of early-game spoilers.