Software Deployment

We in the coming weeks will be deploying about 300-400 Nexus 7 Tablets. The tablets come with 4.4 KitKat. So I have a couple of questions.

1. Currently all of the devices I have added to the MDM with 6.0 are just showing up as one device. Anytime one checks in it just overwrites the serial but does not see them as separate devices. Anyone know why this might be happening or what the solution would be?

2. Is there anyway to create an image or a script for the MDM to automatically update to 6.0. As an image I have a few fully done with exactly what we want from settings to app data. It appears that from my research the devices must be rooted in order to do this but I am sure there are resourceful geniuses here that would have a better idea. Can we image these or automate the process so it doesn't need to involve constant manual checking for updates on initial setup?

Thank you for your responses ahead of time, any responses can be helpful as this is a new project for us. We are quite familiar with K1000 and K2000 but not much besides the basic management in the K3000 thus far.