I think it is nothing unusual if they don't do the mating dance thing, some roos do and some don't. How old is the remaining rooster and what breed is he?
First of all, she is beautiful. Second, it is not unusual for chickens to change colors after a molt. If you did not change her feed or anything like that, then I would guess it is just a molting thing. No worries.
Welcome to BYC! I am a huge fan of Salmon Faverolles because they are so cute and nice, but here is a great chick selector tool to find a chicken that is perfect for you and your situation.
http://www.mypetchicken.com/chicken-breeds/which-breed-is-right-for-me.aspx
Hens go through laying cycles. The eggs are always darker at the beginning of the cycle and lighter at the end so that could be all that is happening. How long has this been going on?