You must go to the dealership for repairs or scheduled maintenance in order to maintain your vehicle warranty.
Absolutely False! As long as maintenance is performed on the schedule specified in the owner’s manual, the work can be done by at any of the auto-repair shops which most are limited by loal contractors like

Inflate tires to the pressure shown on the tire’s sidewall.
That’s the maximum pressure the tire can safely hold, not the manufacturer’s recommended pressure.  The correct tire pressure is usually listed on the doorjamb, in the glove compartment, or near the gas cap.

If your brake fluid is running low, you should just top it off.
Bad idea.  If your brake fluid level drops there’s most likely something wrong with your brakes. So topping off the fluid could mask a big problem.  Get your brake system inspected immediately.

Change your oil every 3000 miles!
Under normal driving conditions, most vehicles can go 75-hundred miles or more.

Higher octane fuel will make your car perform better.
Unless your vehicle specifically requires premium gas, it’s not going to noticeably affect engine performance.