Every time I mention my theories, I get wordy and then they get ignored so I’ll keep this one brief. I believe that the Cylon planet they discovered isn’t Earth, it’s another signpost. Kara turns up and says I know the way to Earth and I’ll take us there and we learn that she followed her own signal to her apparent dead body.
We know she is the Harbinger of Death and as someone else stated this brown crap planet isn’t the home we think they’re after. They showed Earth identifiably when she said that line, but they didn’t show Earth identifiably when they landed. I still believe that they’re almost home and the occupants of the 13th Colony are watching to make sure whomever made it to the ravaged Cylon homeworld are trustworthy.
What is Kara, I don’t know, it’s hard to say. Whatever she found on crap brown planet shouldn’t be her either if Lee saw her Viper blow up in the storm. I’m guessing that either Ellen isn’t actually the fifth and Kara is, or she’s actually “the thirteenth”, a whole new model that we’ll see clues to in later episodes.