I use about 3oz. (I think it's about a 1/2 cup) of light DME mixed into 1L of water. Boil 15 minutes. Cool to 70. Aerate. Pitch Yeast. Decant and add yeast cake to wort when you have reached krausen.
no. the plate handles gas exchange for you. im told its best to set the speed to only create a minor demple in the surface. (my stirbars finally arrived the other day)