Toyota Repair: Wheel Bearing Noise?, 2001 chevy prizm, front wheel bearings

Question
Ted,

I have a 2001 Chevy Prizm, which I understand is a Toyota Corolla with Chevy emblems. I have a fairly loud humming noise while going straight down the road. The noise goes away if I am in a right hand curve. The noise is the same regardless of road surface or tires being used. I assumed it was in the front wheel bearings so I replaced the bearings and hubs on both front wheels. The noise is the same. So I have purchased a rear hub assembly and I am going to guess at the left wheel because I now hear other new noises coming from there. Although frankly those noises could be brake related because I recently did the rear brakes and maybe I did something wrong. I have 3 questions about this problem.
1. Was it necessary to put additional grease in the front wheel bearings? The Toyota factory service manual I have said nothing about greasing the bearings. They were SKF parts and came with yellow grease in them. Not wanting to contaminate their grease with an improper grease, I left them as they came. Should I have greased them? If so, with what? And is it too late to disassemble them and grease them? I have about 120 highway miles on them so far.
2. Is one rear side more likely than the other to have the bearing problem or is my guess at the left a reasonable one? As far as that goes, could the problem be something other than a wheel bearing?
3. Does the rear bearing/hub assembly require any greasing? It is also an SKF part. The instructions that came in the box say to "Fill knuckle cavity with multipurpose grease." but the instructions seem to be describing every hub made and may not apply to mine. (The boxes for the fronts contained no instructions.)

Thanks in advance for your help and expertise, my Prizm has 325,000 miles on it and I am trying to make it ride like new or as close to new as I can reasonably get.

Curt

Answer
The bearings don't require any additional grease, they come prelubed so that's not the problem, it does sound like the left rear bearing is causing the noise because you said the noise goes away when turning right which causes the weight of the car to shift off the left bearing, these are usually sealed and prelubed as well.