Pads or pads and rotors?
Pads are probably a 13-14mm wrench or socket. You can use the jack and lug wrench in the trunk.
Rotors too, would be an 18-19mm with sufficient length for leverage.
Vibe is mechanically Toyota. I would expect the front caliper bolt heads to be 14mm and bracket bolts to be 17mm or 19mm. rear caliper bolt heads maybe 12mm or 14mm and bracket bolts 14mm or 17mm. Bracket bolts might have 21mm heads.
Most brake rotors for asian makes have threaded holes to ease rotor removal. The usual size is 8mm diameter by 1.25 thread pitch. Have two of these (or four if you live in a rust prone area) and something to turn them as well as a soft face mallet to remove the rotors unless you're not removing them.
You also need a suitable tool (such as a C-clamp or large pliers or purpose specific tool) for reseting the caliper piston. A toothbruch sized wire brush is good for cleaning the crud from the caliper brackets.
A small prybar or a screwdriver that can substitute for a small prybar is a good thing to have on hand.
If the brakes have been done by someone other than you in the past (even a shop with a decent reputation) you need to be prepared for the bushing on the guide pins (that's the name I like; I hear them called slides a lot) to be swolen. There should be one pin with a rubber bushing at each caliper and one without. Often, the pins will be lubed with an incompatible grease that makes them swell up and the swolen bushing keeps the pin from sliding smoothly. The grommet should be replaced, but in a pinch you can just remove it using a pick, hook, or small screwdriver. Going without the bushing can contribute to brake noise. If the bushing is replaced, it is necessary to remove all of the offending grease. I use solvent and a small round wire brush for this but use what you've got available.
Two bolts for the caliper and two more for the bracket that holds the pads. If you intend to remove the rotors to have them turned or to replace them that bracket has to come off. Even if you are leaving the rotors in place it can be worthwhile to remove the bracket to clean any accumulated brake dust and/or rust from the surfaces of the bracket that contact the pads and lube those same surfaces. If the pads don't slide freely in the brackets you may experience accelerated or uneven break wear and possibly uneven braking or brake drag.
If you're used to the older styles of domestic make floating caliper disc brakes where the pads are held in position by the caliper itself, the caliper mounting bolts bolts, or the knuckle itself you will find this setup is different and quite a bit simpler. It works well and doesn't have to wear out and lose efficiency over time. I think that once you see it you'll like it.
Using a C-clamp, slowly compress the caliper before you start removing the guide pins to remove the caliper from the bracket. Less of a chance of jamming the caliper piston than compressing it after removing the caliper.
When you compress the caliper, it will push brake fluid to the reservior. I'd swap out the brake fluid in the reservior at that point.
...If the brakes have been done by someone other than you in the past (even a shop with a decent reputation) you need to be prepared for the bushing on the guide pins (that's the name I like; I hear them called slides a lot) to be swolen. There should be one pin with a rubber bushing at each caliper and one without. Often, the pins will be lubed with an incompatible grease that makes them swell up and the swolen bushing keeps the pin from sliding smoothly..
That's a good point.
I've run into this many times and have gotten away with cleaning the bore, pin and bushing, re-lubing it with Sil Glyde (or silicone grease) and reinstalling, but like you say, it still fairly stiff to move.
I never considered removing the bushing all together. I bet that's better than leaving a heavily swollen one in place.
To the OP, I replaced the front pads and adjusted the rear drums on my Mom's 2008 Vibe some months ago (late 2011). Used Carquest ceramic pads. Piece of cake. I didn't need to replace the factory rotors yet, but removed them to apply never-seize on the hub face, so they'll come off easier when I need them to. Like said, they had the bolt holes in the face to help pop them off.
Rear drums also had the bolt holes for removal and came off easily. I blew out all the [censored], lubed up the star-wheel and snugged up the shoes. Mom's 2008 doesn't even have ABS.