1. When my wheel bearings went it sounded like a tire noise, I guess if they were really shot you could get a screech - the axle joints will click on turns under power when they go bad. at 150K you are right at the mileage where these wheel bearings fail.
2. I don't see why you would have to, but It wouldn't hurt
3. I went with the Volvo brand (available at fcpgroton for $159 each. You get new bolts with the Volvo brand - no problems, perfect fit
4. I would look at all of the suspension parts, brakes, axle boots, etc.
5. Don't know

PS - I would go ahead and change both the Driver's and Passenger side bearings. The passenger bearing will be failing shortly if not already.
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1990 240DL - 201K, 1994 850 Wagon - 161K, 1989 Ranger 238K