zypper repo management enterprise Best Practices?

As the Update repos have gotten enormous (12.3) and many more months still to go until 13.1, I'd like to consider how best to update multiple openSUSE machines.

Have searched, not found anything written for openSUSE.
I imagine something might exist for SLES/SLED, if the actual tools aren't available for openSUSE, is there at least public documentation what is implemented?

Ideally, I'd imagine that the zypper metadata would be stored in a network-accessible location.
Only one machine need refresh the metadata, maybe daily (yes, modify the metadata TTL, I know this can be done)
Whenever zypper is run on any machine, instead of metadata located on the local machine the shared metadata is referenced.
When a package is downloaded, the package ideally would be also be cached on the network (squid proxy?)

Solution should support both physical infrastructures although my primary purpose is virtualized machines.
I prefer not to use shared and partial disks although it would likely ease updating because I dread the idea that a problem with a base disk could potentially corrupt numerous VMs.

Ideas?

TSU