few questions on blu-ray

[oxygenuk]

a few simple to answer questions for some of you i think, anyway here goes :P ..

1. will all blu-ray players support dvd playback? or will there be dual laser blu-ray players thast u need so u can play dvd format?
2. will there be home cinema/hifi systems wth blu-ray integregated like dvd home cinema/hifi systems nowdays, and how longer after the public release of blu-ray in the uk u think?
3. how much diffrence in picture and sound will there be? :P :P