Regarding shotgun vs. pistol. When I was 9, my grandfather took me out to hunt grouse. By the end of the day, I could hit a bird. Through my teens, I went to pistol ranges fairly regularly (hey, it was fun) and also got some expert advice while volunteering at the world police and fire games' pistol range. I never attained any level of expertise during that period, and I doubt that you, as a casual non-regular user, would do any better. I could hit a target reliably. Whoop-de-doo.
My first preference is to think long and hard about your situation. Do you really need a weapon? Would you be able to use it if called upon? Finally, are you willing to take the personal risks associated with owning a firearm (it may be used against you by a burglar; it may be used inadvertently in a family dispute; or the absolute worst-case, suicide). Bear in mind that I really liked shooting, but given my current circumstances I would never bring one in to my home.
If you can answer all the above questions affirmatively, buy a simple, small-gauge shotgun. It's easier to learn, easier to shoot, easier to aim, easier to maintain, harder to steal (pistols often "take a walk", shotguns and rifles almost never), easier to store (you're absolutely, positively going to get a gun safe, right?). And a hell of a lot more intimidating. There you are.
