After Import to group, individuals in that group not showing up as recipients to in CiviMail.
When you look at Groups tab for one of the imported contacts, is the status of the Group "Added"?  My suspicion is that the status is "Pending" and thus it will be excluded from use.

Pending is used by CiviCRM to allow permission by end users to use the email address and is used when the Group is set as "Public Pages".

You should make sure the group is set as "User and User Admin Only" which should remove the permissioning component.  (I think you need to reimport the contacts, or at least re-add them to the group once the setting is fixed.)

More on this can be found in the Visibility section here: http://book.civicrm.org/user/current/organising-your-data/groups-and-tags/