When entering the house through the doorway, should my wife let the dog in first or the dog to follow?

We make our dog sit at the door and give us eye contact. If the dog is expected to perform an exercise - sit and look up at us before we open the door then the dog can go first. The dog has basically submitted to you and a higher ranking family member.

Here are a couple of DVDs you should consider:

Establishing Pack Structure with the Family Dog
The Power of Training Dog with Markers
Basic Dog Obedience