Hmmmm.... Yeah, check your CV joints. I just run my hand all around the rubber boot, if you hit alot of grease and can even feel the tear, you know what you got. Be weary about driving like that though dude. It can be dangerous. As far as shimmy at highway speeds, you may want to have your tires balanced. As far as cost, just for the parts alone, you can spend an easy 100 bucks. I dropped about 120-ish for doing both of mine. Although, I replaced the CV myself, so I didn't pay labor
DChriste - As far as a scraping sound, brakes will do that. It can either be worn pads or warped rotors, even lots of brake dust can cause squeal. For dust, you can find brake parts cleaner. As well, not applying the brake pad grease to the back of the pads when replacing may lead to squeal because the grease helps to "soak up" alot of the vibration that would lead to what we hear as "squeal".