Welcome to archery. I've got my answers to your questions.

Don't leave your bow strung. The laminated wood limbs will weaken over time. I hang mine either vertically, by the string or horizontally, with supports spaced just longer than the riser. Do not prop it in a corner on one limb.
The Fred Asbell book on instinctive shooting has a good section on bow tuning. I'm sure there are others. With a recurve there is not much to it, but there are some rules you need to follow.
Accuracy is entirely up to you. To some it comes easy, some it takes longer. If you pick your spot and follow through, you'll have good accuracy. You can acheive it as soon as you can pull and hold your bow long enough to lock on to your target and release smoothly. The range you are comfortable shooting is dependant on you confidence. If you can put all your arrows in an 8" circle at 20 yd., There you go. If you can do it at 15 yd., there's your range. You have to know that, when you pull the bow back, you are capable of hitting your target. Good luck. Above all, have fun.