[tsubaki]

FERM and smoke do have valid points.

I normally carry one of the spare props I have tested previously, not to mention the stuff to install/replace it with, all the way down to the thrust washer.
The prop composition usually depends on your habits, I happen to like the stainless.

Other spares also depends on your habits. I usually keep a spare portable bilge pump with alligator clips and hose connected, spare drain plugs, fuses, oil, anchor/rope, one more safety vest and throwable than needed. If offshore fishing or camping or riding the grandkids around there will be other things added to the pile of stuff.

Depending on what your jack plate setback is and how you normally load the boat, you might need to raise the engine yet higher than a regular transom mount. A 5" setback might need to go up 1 or 2 bolt holes, a 10" might need to go up 2 or 4 bolt holes.

If you don't have a prop already, I'd expect to start out with about a 15x17" stainless and go from there. If the engine is setup correctly and depending on your habits you might need to go to a 15" or 19" and/or anything in between. This is where a dealer setup situation will save you time/money and get the best performance.