BSG & Earth

I was rewatching season one in anticipation of the premiere of season two last week (we're a bit behind here) and I started thinking about the "thirteenth colony." The fleet is headed towards Earth because the cylons have destroyed their homeworlds (or rather, bombed the heck out of them and are now hanging around for some reason - Caprica, at least, remains intact, though full of radiation).

The fleet is also aware, however, that there are cylon agents hidden among them.

Not a problem for Cmdr. Adama - he doesn't actually know where Earth is. But President Roslin believes she is destined to lead the survivors to Earth (and since they've already found Kobol, it's conceivable she's right). She never considers though, that she will also lead the cylons to Earth. Real smart.

Now I know there aren't a lot of options for the fleet - they will likely have to settle somewhere eventually, but shouldn't Roslin consider that she risks destroying the last colony if the cylons aren't removed from the fleet first?

Second, if the fleet does make it to Earth, what will it be like? Is it 'our' Earth? An 'alternate' Earth? If it is 'our' Earth will it be the present? Or will it be Earth 1000 years ago? Or 1000 years from now?

Assuming that in the BSG 'verse, Earth does exist.

Just something I was thinking about.