Quick question about Fantasy

If I have set on my roster a player that is going to play today and tomorrow, but I want to add/drop him for someone else for my next week roster. Would I be able to do that right now, and I will get the points of the player that I have at the moment, and then it changes itself for next week, or should I wait for NA's week 1 to finish?

Also, is there a limit to the add/drops I can do?