You shouldn't need an impact gun to remove those bolts. If you do plan on using one to take them off, just be careful that you don't snap them off, and whatever you decide to do, do not use it to put them back on.
Basically every local automotive store will rent you the tool to compress the caliper pistons for free, so might as well just use that.
What type of brake pads you want/should buy really depends on what you do with your car. IIRC TireRack has a comparison thing when you go to brake pads. (which ones have more bite, less dust, what they're made of, ect...)
You should probably change your rotors while you're there, it will only benefit you. Do you need to? I don't really know, the only way to tell if they need to be replaced is by looking at them. IMO if you're going to have the caliper off you might as well just change the rotor anyway.
Here's a link to TR for you, if you look under the photo's it has a "rating" system to tell you about the pads. Also, next to the name of the pad, it tells you the use of them.