If I am you are going to adore her I have 6 Speckled Sussex girls and there is not one of them that don't want to be held and follow me around like little puppy's. LOL
I have just ordered more because they are just the sweetest! they have it all, looks. personality, and for a chicken there very smart! I know you said you got her/him from Ideal but the discription of the SS chicks on the Murray McMurry site is by far the best I had little buff chicks and darker chicks in my mix of SS girls. Oh and they are excellent layers too, My 3 yr old UNO still lays 6 eggs a week! Sandy
SS have white skin and white is dominant over yellow so it would be hard to lose even if they did some crossing. So, unless you were mistaken about the yellow feet, that's not a SS.