1 - Must the computers be set to the default of "WorkGroup", or can they have their workgroup name be something else? By this I mean they both would be equivalent, just not the default.2 - Do they have to be set to the same time zone? Or is the time check to join a homegroup based on UTC?Thanks.

You can change the workgroup to something else. Think of it as a bucket. As long as all computers are in the same bucket (or workgroup) they can access each other's shared filed. But the bucket can be named anything. They do not need to be set to the same time zone.

Yes, you can change the Workgroup name. However, when creating a HomeGroup, please assure that all the computers' times are in sync.Thanks,Novak