If I were you, I'd make the trip to napa. You may pay a little more, but you know you'll be getting a quality part that will have some sort of warranty.
It may take some extra time the for your first brake job, but you should not have may issues. Use a digital camera and take lots of pictures so you can compare as you move along or show us if you get stuck.
A few comments:
Once you get the brake caliper off, leave the rear pad on the caliper (it will be spring pressed into the caliper piston), use the c-clamp against the old pad and back of the caliper while you slowly tighten the c-clamp. The piston will move all the way to the rear of the caliper. Remove the old pad once the piston is all the way back. It will pull right out. The piston will stay seated and not move. Try not to let the caliper hang by the brake line. I usually let it rest on top of the upper ball joint, although, in the past, I'd hang it on a piece of hanger I had cut and bent into a 'U' to hold the caliper
Now is a good time to check the caliper pins. This is most likely where the two mounting bolts traveled through a sleeve (bushing) to secure the caliper to the bracket. You will notice that each side has a small rubber boot (think of it as a tiny shock boot cover) by grabbing each side (thumb/fore finger) you should be able to slide the sleeve back and forth. There will probably be some resistance, but should still be easy to move. IF your are feeling confident, you can pull these boots off and apply a bit of brake grease to the inside of the boot. The boots are sort of captured by a small lip on the sleeve and will go back on without much effort.
Now take your new rotor and put it on. Grab one of the bolts used to secure your wheel and tighten it up by hand so the rotor is held in place. Put the new pads on. Pay attention to the orientation of the pad. Obviously one will be seated into the caliper piston and the other will lock onto the front of the caliper. One end of the pad will have a 'slot' (bottom) and the other will not (take a look at one of those pictures you took before you removed everything). Generally, the 'slot' end will be on the bottom and ride along the caliper bracket foot. The other end (top)will simply index on top.
Slide the caliper into place paying carefull attention to moving the sleeve (remember the boots) to the rear of the caliper. This will allow the caliper to slide into position. Lubricate the bolts with the brake grease also (before you slide them into the sleeve). Now scecure the caliper with the bolts and tighten it up. I usually go for 'snug". The manual says 15 ft lbs of torque. Snug is fine, don't go crazy here.
You will probaly want to spray everything down with some brake cleaner before you attach the wheel. Grease from your hands is likely to be everywhere. Lots of smudges on your rotor...
Next... Put your wheel on and go do the other side now...