on the size issue of your question it depends upon the size of the snake your considering of getting. if the gtp is a neo to yearling I would not suggest a cage of that size. if its an adult it would do more than great in there.
regarding the pushable screens just remember every snake is an escape artist and you wouldnt want to risk it. modify it with wood or acrylic, exos usually need that type of mod anyways for humidity sake