We're looking at ordering 8 ducklings as pets for our kids. I've read the Storey's guide but still have a few things i want to be sure we have correct before we place our order. -First is having a drake a good idea with them being the kids project or would it be better to just keep all ladies? Does having a drake affect the happiness of the girls? We were only planning to get 1 drake if we get any at all. -Is it ok to mix 4 different breeds together? We were looking at getting 2 each of Buff, Cayuga, Swedish, and Runners. -Will a 4' x 8' coop with a 12' x 12' run be enough room for them? For their safety free-range is not an option with our local wildlife but i also don't want to make it unnecessarily large especially for winter. -The Storey's book says that i have to supplement Niacin, do i really? Everyone i know with ducks just feed them regular feed and doesn't supplement. We're going to be using DuMor feeds (starter, grower, layer) as that's about all we have available to us. Agway is the only other we can get here. -Will feeding layer actually poison a drake with calcium if we have one? The Storey's book says that. Again i don't know anyone locally who's had a problem feeding everyone the same feed. I think that was all i needed to know. Thanks so much for the help! The kids are so excited.