I don't have any suggestion for the "ductwork" noise, I can't imagine how HVAC ducting could be affected by the toilet. As far as the valves leaking, there are two places a valve can be leaking. If the leaks are coming around the valve stem, try gently tightening the nut around the stem. There is sealing material called packing that prevents the water from getting past the stem, and sometimes through normal use, this packing wears away a bit and the nut need to be tighnened. Don't overdo, just enough to stop the leak. The other place a leak can occur is where the valve screws on the the water supply line. If this is where the leaks are, I would recommend shutting the water supply off then removing and reinstalling the valve. Many people like to use the teflon tape to seal these connections, I prefer the old fashioned pipe "dope". It's a heavy paste and can be a bit messy, but with reasonable care the mess isn't so bad that it can't be quickly wiped up. Some folks even use both tape and dope. It's sort of "Different tokes for different folks". Use what you prefer and reinstall the valve. It should be tighten well, but not so much as to twist the supply line. That's no joke, a wrench in the hands of an over zealous strong man can really do that. It is possible that just tightening the valve would do it, but I would assume that if that is the source of the leak, you have already tried that.