Answers to a few of your questions -- NONE of which are dumb. :D
Cast Iron skillets can be used for almost every kind of frying: shallow, pan-fry, deep (depending of course on how high the sides are), pan-grill (as in searing and finishing steaks and chops). Also for baking THE BEST cornbread. There are several good brands -- I have Lodge, which is very good. And best of all, cast iron is inexpensive and if handled properly will last for generations. (Just don't drop it!) It's not great for stewing or braising, because the moisture can cause problems -- although a properly seasoned cast iron dutch oven is great for those.
Before you use a cast iron pan, you have to "season" it. That means sealing the pores. This makes it relatively non-stick, and keeps it from rusting (the biggest problem, other than how heavy those things are.) It takes a little while to season one, but once it's done, everytime you use it you tend to improve the coating. To season a cast iron pan, you coat it inside and out with a very thin layer of neutral, edible fat -- Crisco or vegetable (not olive) oil, and bake it for an hour or so. Wipe off any excess, and repeat. (It's a little more complicated than that, but not much.) Then the first few times you use it, after you clean it but before you put it away, you coat it very lightly again. (Lodge pans come with a label that tells you exactly how to do it.) Eventually the pan will go from metal-grey to black; it might look funny, but that's what you want: a sealed, "seasoned" pan.
There are some conflicting opinions about cleaning cast iron, so I won't go into detail. The main point is: don't scrub off that seasoning!!