To answer your question about introducing a family troup into the wild. You need to understand a little about the troup structure.
A family troup consist's of one mature male silverback, several unrelated mature females, and the juvenile offspring. These are tight knit groups and outsiders are frowned upon. Any male offspring once mature, must either fight the reining silverback or leave the troup.
Gorilla's mature around age 10. So the mature members must be raised for 10 years in captivity. You cannot accurately simulate the wild environment for these animals in captivity and their lifes necessities will be provided by humans. So the gorilla's will learn that humans will provide them with food, water, etc. Wild animals thinking that humans will give them food is not a good thing.
Gorilla's also move in regards to the dry and rainy seasons in the lowlands, and move in accordance with where fruit is ripening. These are learned activities and frequently the same troups will visit the same tree's just as the fruit on them is ripening year after year. These are learned behaviours during the first few years of life. Being raised in captivity cannot teach these necessary life skills to gorillas.
There has been success in taking orphaned young animals and releasing them into controlled environments. However these animals still require humans to provide them with food, as they are unable to find sufficient food on their own. There are very good programs for orangutans in indonesia and for chimps in Africa, in controlled environments.