You should replace the hardware that goes on the caliper (bottom right guides in the pic) but the new pads have the shims already attached. I would not reuse the OEM ones. The new pads have a metal with a dampening material on them. No need to transfer the old shim over.

One heads up. This is brand specific but typically only two of the four pads have the wear indicator metal bit. That one should be placed on the inside of the rotor. If all 4 pads have them it's a non issue.

 

I have replaced brakepads many times. I always clean up the stainless backing plates with wire-wheel and reuse them.
Often, I reuse the OEM stainless holders (anti-rattle clips) too... the cheep chinese knock-offs are often poorly made.

Also beware that the pad-holders (underneath the stainless holders) should be cleaned down to bare metal and brake-greased before installing the holders. NO GREASE goes on the ends of the pads nor the holders. The same goes for the end of the piston and where the outer pad touches.

BTW: Regarding the squeelers (wear indicators), not only do they go on the INSIDE of the vehicle, also beware they are 'directional' and must be placed in the proper direction. (dont get the left/right pads interchanged)
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If you are having trouble with any of the above (you are a visual learner), please check out uTube "South Main Auto" channel. Eric has several how-to brake videos.
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Some torque specs etc from the SM

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