The right colorspace to work with

Hello,

I am currently working with some DSLR footage, which is YCbCr if I am right. (5D Mark III)

Which colorspace like sRGB or Rec. 709 is the one I should work in?

And which colorspace is the best when exporting for web, modern HDTV and for additional work in Premiere Pro?

Should I leave the color management switched off in this case?

I use AE CS6.

Thanks for some advice