As far as codes go 99% are formated with a letter followed by 4 numbers. The first letters are, P for Powertrain, C for Chassis, B for Body, and U for data communication. There are a few exceptions where they put a alpha character in the 3rd or 4th number position ( P02A1,P02ADor P040D) however these are mostly used in diesel trucks. Also DTC's often include a symptom code for example C0035 sym 00. Those extra digits tell the difference between an open or intermitant. OK enough genaric info about DTC codes
So now for your codes...
U1064 loss of comm with the BCM) Often these codes can be dismissed if you are not having major issues. For example if the bcm went down nothing would work right from turn signals to the odometer.
C0899 low system volts) Often caused by low battery power. So if it is a history code ignore it
C0035 LF speed sensor circuit) this code has a sympton code to go with it but for the moment it is not that important.
So we have a problem with the LF speed sensor. Judging by the symptoms you are talking about you have a intermitant sensor. I have had this problem with several customer trucks also my father and landlord's trucks. The way I fixed it was to replace the wheel bearing and sensor as an assembly. Because unless you know what parts you have, you have to remember that GM and after market parts don't always work well together. Another side is that for what you would pay for a GM sensor(without bearing) you are close to the price of an aftermarket assembly(with bearing and sensor).
But before you go all crazy and replace the assembly. Check the back of the hub. It is open to the world and sometimes a piece of rust could get in there a really mess with ya.
Also there is a TSB #PIT3460Q that states to have the tech check the the data in the ABS unit to determine which hub is bad. I have seen this bite a coworker in the
!!!! He put in a LF hub because that was the only code. IT DID NOT FIX IT! After that we found this bullitin. It only applies to Colorado/Canyon trucks. In the data menu "Event History CAL data 5" will have numbers in it. These will tell you for sure what to do. For example 0=no problem,1= RF,2=LF,3=LF+RF, on up to 7.
The rotors are captured meaning they are between the hub and knuckle. So you have to remove the hub to replace the rotor. So if you want to change the rotor, do it when you are replacing the hub. I was also told by GM tech assistance the internals of the sensor are ceramic. The point the guy at TAC was trying to make was not to hammer the sensor on to the hub because you will break it. In my mind if that will break it, then beating the crap out of the hub to get it out to do a rotor does not seem to be a good idea either.