If the gap is created by occlusion from lower teeth and possibly pulling the muscles hence teeth apart thendo frenectomy and resin or veneers to close gap.
Yes, you can definitely re-bond the front 6 teeth. Although, as your dentist mentioned, veneers would be a more permanent solution with a more predictable result.
Yes, you certainly could have this done. It appears that the two front teeth angle out somewhat, so boding would look nice to allign them better. It may even be possible to take a slight amount off of the opposite side of the tooth if they appear too wide to you. The mock idea is a good one...