Yup, those yellow feet mean you've got Jersey Giants. Pinkish feet, are Australorps. My French Black Copper Marans turned out to be a JG, lol! I'd never had either breed, and only figured it out when she laid her first egg at 8 months old and it was a pale rose color.
A great layer, and one of my sweetest birds. She was huge, and always hungry -- man, she never stopped eating!!! A great forager. Sadly, she was more susceptible to the heat, and even though we have a mister system, shade, cool water, she died at a little over a year old. Watch the big gals in the hot temps -- Anything over 80 and she was panting.
And yes, egg color can differ among breeds -- my barred rocks have different shades, as well as my EE's.