Julia is a barred rock
As far as I can tell, the two white ones are not leghorns. I would say white rocks, but they're so big they could be cornish crosses. Look 'em up. BTW, I think the first one is a little cockerel from the size of that comb...
And I think you're right about the welsummers. Though I've not had any before, the welsummer colors are beginning to show in the neck and breast.