Re: 2002 Focus belt tensioner, tire squeal, more probs... need advice
1 - when was your last tune-up; or more importantly new spark plugs? You'd be surprised what new plugs can do to a vehicle. It could also be air related, such as the IAC or idle air controller, which is located around the throttle assembly (approx $40 part). If the dealer did in fact check the belt to see if it's running true, it could be an out of balance pulley, not necessarily a bad tensioner, although it is generally the first pulley to go as it sees the most abuse.
2- zizzing noise - do you have a manual transmission? If so, curious as to when it was serviced last (adjusted if necessary and fluid change)? It might even be something as a worn transmission or engine mount, which can be common on mid to higher mileage compact vehicles. This is most likely NOT caused by the fan belt. You can try a higher quality aftermarket belt (GoodYear Gatorback for instance). However, if the noise persists, install the old belt and hold onto the new one until the tensioner gets replaced. If you have a pulley puller, or some other means of removing a pulley without having it turn relentlessly on you, it can be a fairly easy job for the DIYer. Autozone generally 'rents' parts at no charge, last I heard so it might be something to look into.
3- are the tires wearing evenly? Air pressure is good? If you are turning at a very slow speed, there should be no noise unless at full lock, you'll hear a bit of a 'hiss' from the power steering box. You can also try a tire rotation, to rule out any tire imbalance problems. Worst case is that a wheel bearing is bad, or at least starting to go. Once you hear a grinding noise that increases with vehicles speed, then the bearing is SHOT.
As for the replacing the ignition cylinder I'd try a locksmith, but shop around and check for reviews online first as they can vary widely in customer service and satisfaction. If your vehicle has electronic locks, or worse, a security system, some lock smiths might refuse to do the job if it's very intricate. In some cases here it wouldn't surprise me to see a locksmith driving out to the dealer to do the work, but the locksmith in question would be favorable for that dealer, and most likely, somewhat experienced in vehicles.
It's just sad that Ford would outsource the work, and charge three times as much. When the cylinder gets replaced (if it's not causing you problems, then let it alone of course), make sure to SAVE the original key, and use it to cut other keys that you can use on a regular basis. Every few years, break the cut key in half, and get another copy made off the master. It also looks good when you sell or trade the vehicle in, having a factory key that's never been used. It might be too late for that now, but, now you know one of my secrets.
if you have the means, you can check the front wheels for a bad bearing yourself. All you'll need is a jack (spare tire jack will work fine), a pair of gloves, and if you have it, an axle stand for greater safety: Raise a wheel and place one hand on the top and one hand around the bottom of the tire. Try to tilt it towards you and back again. If there is any movement, then it's more than likely a bad wheel bearing. If there is no play, have a glance at the ball joints, CV joints, and anything else that might look broken (plastic boot for instance), or not connected securely. Then, try the other wheel.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!