I don't mean to sound sarcastic but if you have a garage full of tools and don't know which ones to use, I would think that maybe you don't have enough experience to attempt this task.
You also did not tell me which edge you want to trim. Is it the height at the top or bottom or is it the width? If it is the width you run into two major issues; The hinge side needs to be strong to carry the weight of the door. There fore any trimming from that side may weaken the hinge mount. If you cut off from the other side, now you run into issues of moving the door knob and deadbolt holes. If you move them up or down, now you have to move the door jam receiving holes to match.
Can I ask why you want to go through so much work? And, why are you wanting to use a metal clad door that is apparently not a standard opening?
This all sounds like a lot of work.
If you want a metal clad door to help prevent a dog from scratching the wood trying to get in, go to a local hardware or screendoor company and buy a metal panel that would attach to a wood door.