Based on the ones with the Rose combs.. I would say Wyandottes..... though, I am not familiar with the breed as I don't actually have any yet myself... but hopefully next year!
Self blue and Lavender are the same thing..... just one is a more specific term and one more easily recognized. I would say yes and yes a roo.....
Wyandottes can have single combs. It's a throwback thing and many say they have better fertility??? Nice looking birds