Can a SlingCatcher be able to access any Slingbox or Slingmedia-powered device or do I have to own one?
The SlingCatcher is only compatible with Slingboxes. I am not sure its actually compatible with "Sling Loaded" devices like the Dish ViP 922.
If so, then is there a list of Slingbox IDs which is available to the public?
Slingboxes are privately owned. Most people in your situation will have a friend or family member host it for them.