Hi Randy,
Thank you for your question.
A 48 foot cage is definitely long enough for softball. It has the same #24 netting that all residential cages have, regardless of the manufacturer, so it should last for years provided it is cared for properly. It includes everything - net, cage frame, support stakes.
We recommend removing the net when it is not in use. This will keep any unexpected high winds from taking the whole cage down and will also keep the net from wearing prematurely due to overexposure to the sun and rain.
You can leave the frame in place, since the wind has nothing to catch without a net on it. Obviously, you will want to remove the frame during cold winter freezes so that the fiberglass doesn't crack.