Feeding in a separate enclosure only creates stress. Some snakes will eat in a separate enclosure, but most won't. I just feed my Ball pythons and all of my snakes in their own enclosures/tubs which makes it a lot easier on me and the snakes. If you are going to get a Ball python, I would suggest a tub since it's a lot cheaper, a lot lighter in weight, easy to clean, and holds in humidity extremely well. Ball pythons at pet stores aren't the healthiest, so I would consider purchasing from a good breeder. Try Brian at BHB (www.bhbreptiles.com) or Adam at 8Ballpythons (www.8ballpythons.com) or even Tracey Barker at VPI. There's a lot of great breeders out there with healthy snakes so I would consider purchasing from them. Pet stores are not the best place to purchase a healthy snake.
Also, when you approach the snake, be calm and don't pick it up as quickly. They can get scared easily and some may even strike. My little hatchling Spider struck at me because I moved too quickly, so it's important to pick up the snake calmly. This is what I do when I pick up my Spider and he no longer strikes.. unless I'm quick.