Best practices for Backup Exec 2012 with vSphere 5.X

I have a completely virtualized environment running vSphere 5.X. Even the vCenter server is virtualized (new for me).

What is the best practice for Backup Exec setup in an environment like this? Run on an existing VM (such as a file and print server that has direct access to a large volume of data), or run a separate backup VM with BE installed?

Any issues with snapshots in either of these configurations?

Backups will likely be written to a dedicated backup appliance like the Dell DR4000 (essentially a NAS device) that "hangs off" BE.

What do you use if you have a similar enviroment, and why?