I would assume the chicken has Cream Legbar ancestry due to the slight crest. As other stated, Polish could be a large possibility in the mix because of the fact that they can have both a beard and muffs, along with their prominent crest that all individuals possess. I agree on Easter...
Mixed breed, but can you show us pictures without anyone holding the chicken? Height, the way they stand, feathers we can't see, etc. all matter.
No, a chicken will only lay one color throughout their entire life. The pigment can decrease if their production of bloom decreases, or they can have...