Hope you get it figured out. As far as the oil leak, it is most common, the crankshaft oil seal (Front main seal). I noticed a huge difference immediately after replacing mine. I do have an oil leak still, though not from the FMS. I think it is the head gasket, as the oil pan gasket doesn't have a noticeable drip. It's not nearly as bad, either.
I did have to replace the alternator, though, due to the really bad buildup of oil being strewn about from the harmonic balancer.
Again, from the "stethoscope" method isn't a precise method, and takes a bit of getting used to. If you know your engine well, you could discern more effeciently. I would still venture to think that it would be coming from the water pump? My PS pump on my other car only SLIGHTLY alters it's wavelength when turning the wheel, and does change with the engine speed.
Worst case scenario would be to do as you had mentioned, and just remove one belt at a time. (You need to obviously remove the PS/W pump belt first), then you would remove the alternator belt. Since you've got both belts off, you might as well just remove the crankshaft pulley and replace that annoying oil seal
It would also give you more time to look for other leaks while you're down there.
