With basic care your stained glass art work should last for generations. Stained glass does not require a lot of maintenance and the glass does not degrade with time. It will break however if it is dropped or not handled properly when moving. Generally just wiping your glass down with a damp rag will clean dust off just fine. It is also a fine to use a little spray wax like Pledge to bring back the shine.
Hanging: I always recommend handing your glass work with a metal hook. Suction cups are convenient and often times they are fine but they have been know to come loose from the window and if that happens your stained glass will end up on the floor and possibly broken.
If you order a larger item it will come with jump chain for hanging it. I ship these with chain that is hopefully longer than what you will need. Jump chain links can be opened with two pairs of pliers so you can remove links to set the hanging height to be just right for your window. Smaller items such as sun catchers typically come with a nylon line which is not adjustable. I usually make these so that they hang down about 10". If you need a different length line than that for your window just let me know and I can make the line any length you would like.