Hi, welcome to basenotes.
1. Best way to store is somewhere dark and cool - fragrances deteriorate in light and heat (shame coz some bottles look very pretty in sunlight!)
2. I don't mind imitations if they are good ones. The only one I own is an old Stitch one imitating Tommy Girl. The only reason I don't buy the real thing is because the concentration is very low and I find this imitation lasts much longer. I do not count it in my BN wardrobe though and rarely use it. I know it's tough relying on parents though!
3. Well usually I spray to my wrists, crook of the elbow or neck (I find wrists don't last as long though). Splash bottles or miniatures I usually tip against the skin so that a small amount splashes onto the skin.
Hope that helps!