So far, YES, YES to a point, YES & YES & NO.
The brakes are magnets so the hum you hear is normal, also since the magnets drag on the inside of the drum to apply the brakes you will hear some squealing at times. If it is extremely loud and all the time I would have them check. Since the sway bar is just controlled by friction you will also get squeeks and squeels when turning.
As to lifting the tow vehicle, you won't hurt anything on the truck and is not an unusual practice, a lot depends on the vehicle and trailer. No you really don't need to raise it that high to release the bars, but they are under tension so you could get hurt if there is too much pressure still on them and you aren't careful.
Chrislorl posted while I was typing "he wins"