I think the welsummer might be a roo due to the saddle feathers, the guy I bought them from said he ordered all hens and that I could exchange any roosters. also let me know if you think any others are roos.
I think they are all pullets, if the wellie was a cockerel i think you would be able to tell. By this age, a cockerel would have different coloring. I'm no expert on Welsummers, but I've seen some when they were this age and you could easily tell the cockerels from the pullets.