Re: Ground issue
0.17 Ohms is really a small reading and is something I would treat as "connected" but it sounds like a valid suspect but not sure how that could bring the noise, you can try to replace it and see how it goes but I have other suspects myself. If this guitar has higher output pickups than the other guitars with less ground noise then those may add a bit more noise floor, for example in one of my guitars my guitar the bridge humbucker can have a higher floor noise than the neck stacked single coil, put that thru a high gain amp and it can be quite noticeable. Also, according to what I have read internal shielding copper foil can add noise if there not a proper connection to the physical ground connection where you are connecting your rig, an affordable ground tester can help to verify that, if ground in the outlet is really not connected then copper foil shielding can become just a noise receiving antenna, conductive paint can be a shielding in disguise. There are other things I can thing one can check regarding noise but are not guitar specific and the way you describe it sounds like guitar specific and the fact that some noise goes away when you touch the hardware sounds like you may not have proper ground in the electrical outlet.
Edit: My comment about higher noise floor from high output pickups comes from a comment I got once from Seymour Duncan tech support over the phone, when I was trying to understand why my bridge humbucker had a higher floor noise compared to an almost dead quiet neck stacked single coil. That was a Jb vs YJM Fury.
