Why are you removing freeze plugs ? and no they are not reusable.

There is an NPT plug in the side of the block , in the middle and about half way up between 2 freeze plugs , this is what you remove to drain down the block , draining the radiator usually only drains it down to the bottom water pump hole.

You can take off the lower radiator hose and jack up the rear of the car as high as possible, this will drain more of the block ....