Welcome to the wonderful world of SW
. It's awesome that your wife supports you on this, that can be trouble for some folks.
Keep reading and learning and researching. You cannot spend too much time doing this before you get started.
54g tank is a pretty good place to start. Bigger is better for learning on, as the more water volume you have the more forgiving your tank can be to the typical mistakes everyone makes.
Sufficient live rock and a skimmer is all you need to be successful as far as your bio filtration are concerned, but there's a million and 1 ways to implement this. Airstones are not necessary.
Look into a Sump for your tank as well. This gives you more water volume, and a place to allow your skimmer and heaters and other equipment to work without being seen, to hide the eyesores from the tank. The canister filter isn't necessary either if you go with a sump system.
Stay away from crushed coral. As it has benefits in the beginning, in the long run it can turn out to be a nightmare. Rather use a finer grade aragamax type sand for your substrate.
Keep the questions coming! That's what we're here for.