Best Practices for client installation on Multiple Clients - 10.2.700

We currently run 10.2.400.
On a new server I installed 10.2.700, which is we want to move to.
We have over 50 computers. Some just run MES, others run the full version of Epicor.

What are the best practices for installing the new client on the multiple machines. Should I use AD? Or is there a different or better way?

I would like it to step on the install of the 10.2.400, so users do not feel any difference. Is choosing the same directory as the old version for the new version to be installed enough?

Another question:
The MES computers have the sign-in info in a config file. Do I need to recreate those config files?