Re: 2 volumes 2 tones
I never used the dual volume controls on my les paul, so I did in fact wire it up with a master volume and master tone. I know it is a tradeoff with respect to versatility, but it is more intuitive for me--I know others like the ability to blend the two pickups differently in the middle position, or perhaps do the solo/rhythm thing like you mentioned, so they like having the two volume setup.
It's pretty easy to rewire, so you could always try it and then switch back if you don't like it. Just make sure to label all the wires so you can get them back to stock if needed. Currently, the pickups go to their respective volumes/tones, then to the toggle switch, which goes to the output jack. The easiest, if not cleanest, way to try this out is to simply connect the pickups directly to the toggle switch by soldering together the wires that go into and out of the volume pots. Then, take the output from the toggle switch, which currently goes directly to the jack, and pass that through the volume pot, to create a master volume. If you ever want to get it back to stock, all the wires are still in place and it is a snap.