Don't use projects to track these admin and support activities - they aren't projects, not as I understand their description.
Look at using Other Work and or Services.
1000 resources on a single task - managing dates which are affected by ETC's going to zero - expect the answer you'll get back from Support is "Working as designed."
What you are doing sounds more like an allocation - "We allocate 1000 resources to a Support topic for a year - allocation hours are zero, but the allocation segment length is one year long - don't know if resource will ever book time to topic, and if they do, don't know how much they will book. We just need a bucket for them to put their time into."
I think you will find Other Work and/or Services a better fit, as they are allocation based, not assignment (ETC) based.
You can also group related Other Work and Services into hierarchies in order to keep things organized, as if you were using a WBS in a project.
For example:
- Parent Other Work=User Support
- Child Other Work=PC Support
- Child Other Work=User Application Assistance
- Child Other Work=Network Support
- .....
You might also consider using Incidents (link your ticket system to CA PPM Incidents) where the incidents can then be associated with an Other Work or Service topic, or even to the Application that the ticket is supporting. Users book their hours in your ticket system, CA PPM rolls it up - could then do some high level planning without having to allocate a 1000 resources to each topic - plan using a few roles, import the detail actuals from your ticket system.
My understanding of your problem may be wrong, but if I'm correct, appears that using tasks on projects might be the most difficult solution that could have been picked.