First time broody - questions !!

Hi I have a 1 year old silkie who was always going broody so I decided to get some fertile eggs for her to sit on and hatch out. We live in Brisbane Australia, she is indoors on a thick bed of shavings in the spare bathroom. It is spring here but very mild around 22 degrees each day so not hot or cold.

Questions:-

1) The eggs I picked up from a local breeder. They are silver laced wyandottes - will it matter that they are not silkies. Will she still take to them even though they are a diff breed?

2) Over the last few days she has gone very grey around the face area. She is eating and drinking and pooing although not very much and does seem quite happy. Do I need to worry about this greying? Will she return to norml after the chicks have hatched?

3) I have read on other threads that after the first few chicks hatch they abandeon the other eggs I have put 12 eggs under her. What should I do if she abandeons the eggs or will they just all die. There are about 5 days difference between my oldest and youngest egg.

Any advice greatly appreciated.
Sue