gamerscore

does downloading these game saves unlock the achievements?

No. In the dashboard, it says that you can use the game save under your profile, but your gamerscore won't go up.

im glad it doesn't effect peoples gamescore because that would spoil it.

yup...kinda the whole point

if your looking for easy gamescore, I recomend getting cars matternational. I borowed this game off a friend coz they said it was heaps easy. I finished it in a day (with breaks) and you get an EASY 1000 Points to you gamescore.