Which roo should I keep?

[Dragon Slayer Trinket]

I think you'll get lovely eggs either way. If keeping both isn't an option, I'd go for the nicest one over everything else, and if they're both sweethearts after their teenage phase, pick the prettiest.

 

[nuthatched]

My hens are americaunas, true whiting blue, olive eggers, silkies. In order to get blue, would the Legbar have to be crossed to the blue layers? Or does blue on blue create others?

Blue layer+ blue layer will only make blue layers, also blue+ white layers will get blue.
I think everything else would make green, but unless you have real Ameracauna, you might get green from their daughters.