Bioshock: Vita Chamber and other issues

[Genz]

Hi'!
I finally got Bioshock this monday and I have a few questions. I don't want to look in that other Bioshock thread because it says there are spoilers and I'm only in Arcadia right now.

So my questions:
When I use the vita chamber, does it have any negative effect on me except that I need to walk a little to get back to where I was? I'm playing the game on "hard" difficulty, so there seem to be some villains that can't be finished in one go, like Big Daddys and now the Houdini Splicer.

When I take a photo, it says A, B or C in the bottom right. What's that? Picture quality or something?