To answer the noise question, I will speak only about the original version of the AM 150 watt MH fixture and ballast.
I took my SPL(sound pressure level) meter
and I placed the microphone 6"
from the ballast and took measurements. The SPL was 40 dB with peaks at 45 dB A-weighted. Not exactly scientific but that is the best I can do without an anechoic chamber.
According to the manual typical A weighted SPLs:
Whisper at 5ft is 32 dB
Typical residence is 48 dB; at night 42 dB
Typical large office is 58 dB
Normal speech at 1ft is 68 dB
Vacuum cleaner at 10ft is 72 dB
So unless you have the a dog's hear abilities or use the ballast as a pillow, you are unlikely to hear the hum under normal circumstances, especially if the ballast is inside you stand.