Greyhounds have been bred over thousands of years to chase prey so don't be surprised if yours wants to chase anything that moves.
Having said that, your friend may find that her adopted greyhound, like many of its breed, prefers a comfy chair in front of the fire. Retired racers often seem to be grateful for a bit of peace and quiet.
On the other hand your friend will need to be extra careful when taking her dog out for excercise. Much as I hate those expanding leads (in the wrong hands) one might be useful while the dog and your friend are getting to know one another.
A good adoption charity will be very careful to match dog and new owner and will have done some training before allowing the dog to be adopted. It might be useful to investigate one or two charities before deciding which one to go to.