Unsupported wire in crawlspace
Recently bought a ranch house. The older (1949) part is over a crawlspace. The wires for the receptacle circuits run down there. The wires are unsupported, meaning they run from one outlet to the next without any clamps or staples. The wires are clamped on the inside of the receptacle boxes but that's it. On one of the "newer" circuits that runs to a 1979 addition, the wire is actually lying on the ground (!).
(1) Is any of this acceptable? If not, can I just staple the wires to the bottom of the joists at four foot intervals to provide support?
(2) Eventually I plan to replace the wires because the circuits are ungrounded. Would it be better to run the new wires (a) through holes in the joists, (b) stapled to furring strips, (c) stapled directly to the bottom of joists? I think all options are legal, so is there a preferred way?
For now, I am just going to run a #10 ground wire back to the panel for any receptacles that need a ground. Thought about the GFCI route, but would prefer a true ground for my computer, TV, and refrigerator.