Your tires should be rotated every other oil change, or every 6000 miles. Neglecting to rotate tires is a major cause of premature tire wear.
YES. The failure of a timing belt in many cars can result in major engine damage. The cost of repairing an engine with a broken timing belt is much greater than the cost of a timing belt replacement.
There are many sensors and computerized components that manage your vehicle's engine performance and emissions. When one of these fails, the "check engine" light is illuminated. Although your car may seem to run fine, it is important to have the issue addressed to prevent long-term problems.
This is a very serious problem - if your car overheats for too long, you can damage your engine. As soon as possible, find a safe place to pull off the road and shut the engine off! Do not attempt to check the fluid level in the radiator; the hot fluid can cause severe burns. The best thing to do is have your car towed to the nearest, trusted auto repair facility.
You should get your oil changed every 3000 miles or as recommended in your vehicle's owner's manual.