Don't know if the 2001 is the same or not, but I just bought a 2004 and it has disc brakes in back, which take pads. You can usually check without taking the wheels off... if you look in through the holes in the rims and see a bright shiny metalic disc, then you'll need pads (the shiny area should have no/little rust/dirt, since it is constantly being scraped by the pads. If you can't see any shiny area, then you likely have drum brakes, which take shoes. Taking off one wheel would allow you to see that better, but most rims have holes you can look through just fine.
There is one other thing to mention, though... if you have disc brakes in the rear, you likely have both pads AND shoes - the shoes are used only for the emergency/parking brake. I don't know for sure, but I imagine that those shoes wouldn't need to be replaced very often, especially if you don't use the emergency brake much.
As far as how hard to change... that kind of depends on your comfort level with car repair. I generally consider disc brake pads to be easier to replace than drum brake shoes, mainly because reassembly of the drum brakes can be tricky with all the different springs, etc. that hold the shoes in place. As far as DIY car repair goes, though, they're both probably at the easier end of the spectrum.