I'm using West 105 epoxy with 206 slow hardener and 100gm glass twill to cover the hull. With the smooth side of the twill uppermost, there is less to sand.
To keep weight down, I decided after weighing up the pros and cons of both methods, to lay the glass down on the bare wood and stipple the epoxy through it to wet out the balsa. I know a lot of people brush on a layer of epoxy and let that set first before laying down the glass.
A friend gave me the tip of laying masking tape on the glass in the area you will be cutting it (before you cut it), to stop fraying. It worked well.
I was able to use just one piece of twill. This adapted to the shape of the hull well, needing just a few relieving cuts around the hull edges, especially stem and transom chine areas, to allow the shape to conform properly without lifting.
Chris