Hello:
Always happy to see fellow Americans walking the Camino.
Not sure what your hiking experience is so training advice I will skip for the moment. In regards to shoes, I would recommend an REI store and let them make suggestions. I wore low cut Merril hiking shoes with vibrum soles and Smartwool socks but everyone is different. The same with your packs, they will fit you in the store.
Pack as light as you possibly can and then you will still overpack. Start slowly, I recommend you break the normal first day into two days and stay at Orisson the first night. You need to make a reservation. The first day, I found, was the most difficult. It can have a big impact on the next few days.
Another possibly issue is that you will be walking with others. This can sometime present a problem as very few people hike at the same pace. I would recommend you discuss this ahead of time. In your training you will see the differences in your individual pace. There is a thread that talks about this issue. I recommend you read how others dealt with this situation and think about how you might work differences out between yourselves.
This is going to be a great experience. If I can be of any help, please feel free to PM me.
Ultreya,
Joe