Does your friend have a pool or pools for them to swim in? She's gotta have really big water buckets if the geese can actually get in them to poop in them; I raise the smallest breed of domestic goose and even then they are the biggest birds I own and couldn't get into my buckets like that. I couldn't imagine they would even want to try squeezing in a bucket if they had access to a pool to swim in instead.
Mine are all sweethearts. I picked a docile breed on purpose, and even the ganders are well-tempered and have never been aggressive, not even in breeding season. There's not really a trick to raising them that I know of, I raise them like all my other birds. Probably handle them a bit more as goslings than the other species because they are so, so sweet and smart, and they will talk back to you if you talk to them and love to cuddle. They're probably my favorite birds.