The octane rating is essentially a measure of a gasolines ability to avoid knock. Use the rating recommended by the manufacturer in your owner's manual and do not waste money buying high octane if you do not need it. On autos equipped with larger than standard tires this force is multiplied. Using a steering damper can greatly reduce the problem this presents. Do this at the same time you perfom your regular oil change to avoid forgetting.
All belts wear out.
If your timing belt goes, you risk serious and expensive engine damage. Check your owners manual and replace timing belts as recommended. If the water will not bead, it is time for a new coat of wax. Oftentimes, autos that are parked outside in humid areas accumulate a bit of rust on the pads overnight. After applying the brakes a few times the noise should disappear.