which visa? what documents

I will be traveling with my daughters from USA to China where they will participate in a summer camp program. We have a letter of invitation from the program. Should we be applying for the tourist (L) types? Besides the applications, photos, passports, and itinerary will I need any other documents? One of my daughters was adopted as an infant from PRC; does this present any special considerations? We have traveled to PRC previously for tourism. Thanks for your help!