The OEM size is about 6% larger than what you have now, so your speedometer is likely a bit off. There isn’t too much incentive to change back, really. Stock size is probably cheaper and more comfortable but not significantly. You could also just get 215/55R17 tires which will be the same diameter as stock and that way you don’t have to buy new wheels.

Harness and compression are good things to check, and add the injectors to that list.

Harness and compression are good things to check, and add the injectors to that list.

You got the wrong rotor. Cars often have different rotor sizes depending on the trim level or model year, so it might be OE spec, just the wrong OE spec.

It’s the hose that connects the secondary air injection pump to the airbox

Get one of those plug kits with the two T-shaped tools, vulcanizing fluid, and the rubber strips. That’s the same thing the pros would use. Use that then cut off the excess and you’re good to go. If you want it to be technically correct, take it to a tire shop and have them put a patch behind it, but millions of people just plug it and call it a day there with no issue.

Don’t use any liquids or sprays or whatever, they’re not a permanent repair and the mess it makes will annoy the tire tech.