I can't tell the breed but as for the gender I am guessing 2 boys 2 girls.
I hav 2 chicks which are just over 2 months old, even though you can tell the gender by colour (cream legbar rooster and wellsumer hen) but you can see how different their combs are.
My hens usually only gets big red comb when they are about to lay (5-8 months old).
Agree with other posters as to gender, breed more difficult to say. Might have a White Leghorn rooster(though there are many breeds of white chickens) and a Silver Sussex rooster (because of pink legs, but color may not be quite right). Think the blue ones have some Easter Egger in there crossed with something with pink legs (more Sussex?) Looking at them all, my best guess would be barnyard mix. Maybe ask the private party they came from what kind they had running around out there.