I had a ball python (Python regius, I think) for years too. They are generally very mellow. I ahve yet to see one develop the attitude problem that is so common among larger boidae family members (who frequently get grumpy once they break the 6' barrier, probably due to reduced handling). They seem to like being held (or at least, they tolerate it well) and they like to explore, so let them look around, but don't take your eyes off them for a second. They can "disappear" long before you can't see them anymore (like getting the front third of their body into a sofa as mentioned above). I have heard that some wouldn't eat anything but chicks while others have no problem w/ mice. Many won't do prekilled, so you may have to let it kill its own or you can kill the mouse and toss it in, still twitching.
Personally, I preferred live mice. If the snake didn't take it within 5-10 minutes, I would move the mouse to a small cage w/ bedding, water & lab chows and try again in a week. Sometimes mine would eat 3-4 mice in a month, sometimes it wouldn't eat for 3 months (hence my preference for live mice). Ball Pythons only range from 3-5' as adults, so you never really have to switch to rats. This is a good thing, especially for live feeders as rats are a lot more likely to injure a snake than mice are.
In short, get one that has been eating mice, maybe even watch it eat by appt. They are common in stores, but if you live where there is a herp. club, you may be able to get something more colorful, or at least different from the common morph found in pet stores. Club specimens are also usually locally bred, which is good if you are concerned about collection and importation practices (as you probably should be).
I would like to second the motion for frequent water changes.
I kept mine in a 20L with a big chunk of driftwood, a warming stone and I cut a few scraps of astroturf to fit the bottom. I could just switch one out, hose it off and let it dry somewhere. I would also provide a small shoebox w/ a hole in it from time to time as a hiding place. I eventually moved it and my CA King (L. getulus, striped morph) into a larger, custom built cage.
Newspaper can/will disintegrate, spread odors all over glass, leave ink all over stuff over time... I do not recommend it.