I don't hear mine at all. Only if the fan is on BOOST, and it's just the whoosh of air.
We still have a window unit in a far-flung room of the upstairs, and when that compressor kicks on, you can feel the vibration propagate through the walls. It's got a resonance. Stick frame house, but any material can do that.
Tell you another thing - our wall mounted units (same as window ones basically) also had mold growth we didn't notice until removal. Can't be good.
I don't think I paid much mind to the heating aspect when I bought it. But boy that was a pleasant surprise. It's not going to be too efficient below 25 degrees or so, but for quickly heating up a house or shoulder seasons, it's perfect. I heat mostly with pellets when cold, but between those 2 things, I used less than 1/4 tank of oil all year. It wasn't cold, but that is same ratio as other winters.