Hi Mike -

There are two ways you can assign apps to a group so that new members are evaluated for the push.

1.  In the Manage App Distributions workflow, when selecting the device group, do not check the box next to "Current Group Members only."  By default, a published distribution will target all devices that are part of the selected device group and any devices that meet the group criteria in the future.  Group Membership is evaluated at the time of distribution and refreshed thereafter once every day and when the group is reused in another distribution.  You can also manually refresh the Device Group under Manage -> Device Groups -> Actions -> Refresh Group.

2.  In the Manage -> Device Groups workflow, you can use the Action to Distribute App.  This would apply to all current members of the Group and any future devices.

Regarding the custom attributes, you can export the Devices using the Manage -> View All Devices workflow and edit the spreadsheet to include any custom attribute you want.  After which you would re-import the data using the Manage -> Bulk Update (Custom Attributes) workflow.

We also have the ability via our Cloud Extender to read detail from your active directory or LDAP to help manage groups.

If you need assistance in setting anything up, please let us know