2010 Prius Pre Collision and ABS issues

I was having the pulsing issue with my brakes so I started looking around. Mind you, this was a noticeable pulse that was constantly happening while braking and even at stop lights - If I held the car with a light break, it would rock back and forth. I was thinking a sensor of some sort. While on my way of looking around, I notice the brakes were low. I decided to replace all brake pads with OEM pads and everything went smoothly. Afterward, about a day later the ABS and Pre Collision system warnings lit up my dash and of course, the brakes are still pulsing.... A few questions - before all hell broke loose, I was thinking the constant pulsing was due to a motion sensor of some sort where either it was dirty or malfunctioning making the car think it was on loose ground causing the ABS to constantly pulsate. If this is a good start, which sensor am I looking for, where is it at, and how do I test it. Also, I went and attempted to turn of the Pre Collision by pressing the button on the steering column but it did not do anything with respect to all of the warnings on the dash. I would have thought it would eliminated it some or all of them. For this, I believe it is the sensor behind the hood emblem - Is there anything I am looking for on this? Is it worth testing it or attempting to clean it? Lastly, while I have a buddy that has a great OBD scan tool, I tend to go over and have too many beers and get in trouble with my wife... So is there any good OBD PC software that anyone can recommend along with a USB or Wireless module to connect to the PC to do some diagnostic work. I have purchased in the past some USB to OBD cable but I could never get it to work after many hours or trying different drivers and stuff. Sorry for the long post and thanks in advance for any help I get.