If the pads have enough material on them, they won't need changing. IIRC they're DB1170 for the 4 pot Sumitomo-Subaru fronts (DB1678 for 4 pot Brembo fronts), and DB1156 for the 2 pot Sumitomo-Subaru/Brembo rear calipers?
New pads will come with shims and all that I'd think.
I'd recommend Red Remsa pads (they have the shims etc in box), plus they're good ceramic street pads. DO NOT get Repco RTQ pads - they're easily the worst pads on the market. You probably only need a decent set of street pads anyway.
Clips to hold in the pads should already be with the caliper (minus what you're missing).
I will add that with my car, which has Brembos front and rear, that I have a slight clunk from the brakes when taking off, which is just the pads slipping back and forth in the caliper - I personally don't worry about this, as I know it's a harmless noise.
If the rotors are not at their minimum thickness, you can get them machined - only really need to do this for the fronts, as they do the majority of the braking. You can pad slap the rears if the rotors are in good nick. If the rotors are under the minimum thickness, they will need replacing.