Has anyone used a group visa to China for 2 people travelling as husband and wife?

Nanajo, I personally suggest that you both apply for the single entry L type for your trip. It's more appilcable. For group L type, you might be required to provide the invitation letter provided by travel agency or Chinese tourism bureau. For single L types, you just need to provide return air ticket and hotel booking except for your passport, application form and a recent passport photo.

Yes, you can send all your application materials to the CVASC branch that has jurisdiction in your area. It takes around 10 working days, six days slower than submitting your application on your own or by someone else.