no you cannot breed sheep. you can breed cows or horses, but not sheep.
Wool
yes
This is because the Farmville creation team created it like that.
Because white is the most common color of sheep.
You collect it from your sheep.
Harvest wool
No there isn't yet
it turns into a frog :L
I've played Farmville for a while, but no. Not that I know of, sorry.
Give each sheep you want to breed wheat.
you can get black sheep on farmville by adopting them. to do this go to your facebook homepage, then on the left there is a bar that has different categories for news feeds, click on farmville. now scroll down until you find a black sheep and hit adopt some people may have already adopted them, but keep trying youll eventually get one
The collectible twine can be found when harvesting sheep on your farm.