Does any body know how much brake fuild is suppose to be in the container? Should it be full or at half?

should be around the line on the container

It should be nearly full when all the brake pads/shoes are new. As the pads/shoes wear more fluid goes into the calipers & wheel cylinders and the level will drop. You should check how worn the brake pads & shoes are. It won't hurt to top off the fluid, you can always remove some next time the brakes are replaced. Once you add fluid keep an eye on the level to make sure you don't have a leak.