If i duo with a gold V and im silver 1 with 0 league points, how much will i be getting per win? what about losses?
and if i just reached silver 1 if i lose my next game will i be moved down?

Gold V and silver I are basically the same elo. In the old system it would be like 1450 and 1500 I think. So you should get normal LP amounts for wins.

There is a grace period when you first get promoted so you don't get insta-demoted. How long it lasts for, I'm not sure.

As for the duo, it doesn't matter who you face. Your MMR determines how much LP you gain/lose not your opponents. (At least that's my understanding of it)

what does MMR meaan