For the proper configuration of Active Directory I would look at a post over on ServerFault as that is more of a server configuration item.
From a testing standpoint, your test operation is quite simple.
- Install it on one machine
- Validate that it is functional
- Login to the other machine and validate that the process is still working.
Now, all of this is a bit limited depending on how the roaming profiles are setup, as many times, installed applications are not going to be coming across, their configuration/options obviously will as they are stored in the roaming profile of the user, but the application itself must be installed on each machine, once installed, then settings/options are there across the board.
NOTE
This test scenario does assume that a user with a roaming profile has the same permissions to access every machine on the domain. If you are in an environment where users might have limited permission sets depending on the machine that they login to, you will need to modify the above criteria to include testing on each of the "limited access" machines in addition to a full access machine.