Yes, the fans are connected through an NA-FC1 (NA-FC1) and NA-FH1 (NA-FH1) to the PWM fan headers on the motherboard. So, the fans can be controlled through the IPMI fan settings and then tweaked if desired with the controller. You won’t need the install instructions, but if you want an idea of what is installed a link to the instructions is here; Exciting Update - Noctua Fan Kit Available for Purchase! - #20 by astraea.
Everyone has different thresholds for what they find noisy and what types of noise they find distracting. How big a room you have, if the rack is enclosed, etc will factor in. I doint think people generally find HDD noise to be loud, but some people find excessively clicky drives to be distracting. My HL15 is in another room, as much as anything because I have that luxury. Based on my prior experience with a Q30, which was in the same room as me, I don’t think I’d have a problem having the HL15 in the same office room as me with the fan upgrade. The drives in that weren’t that noisy. Unless you are looking for near quiet becase you are doing audio production or on lots of conference calls, etc. If it was a home theater room it might still be a bit noisy, but others seem really pleased with the low noise of the fan upgrade from what I’ve seen here.
My understanding (I can be corrected) is this is a feature of the HDD backplane that seems to work with most modern drives. I forget, but there may be some drives it doesn’t work with, I seem to remember something about certain pins on the drive connectors used to support this. It’s not going to be something in the OS, as this happens before the OS loads.