Sue, we run all of them together outside of breeding season and the few breeds we keep get along. We have two Sebbie ganders who hate each other, so they tend to keep their distance. Why no white Sebbies for you? They are very stunning. The colors are great fun too, but much more work needed with them to breed good confirmation into them.
All I can say is do your research and ask lots of questions. There are a large number of "collectaholics" who don't have good stock, but breed anyways selling the offspring. Seen a number of supposed Sebastopols recently that look off for lack of a better word.
Yes a good house is needed, but if you are talking goslings then he has a year to build it.
if he builds it they will come.