RG's usually use 500k pots. If i remember correctly 250k will roll of some highs (often used on Strats or with the ice picky SD JB pickup) and 1meg pots will roll of some bass. You will need the knurled shaft type to fit standard RG knobs. Longs shaft pots are for Les Pauls and will be way to long.
Audio for tone, linear for volume, although some guitars use audio for both but I suspect this is whats causing your volume knob problems.
Shank length wont make much difference as you can put a washer inside the body to lose a millimeter or 2 if needed. But again if remember correctly a 10mm "shaft" push/pull I put in one of my RG's was about 1mm to long, but all that did was make the knob sit a little high and possibly could have been fixed with a washer. Just go of the measurements "Rich" posted or have a look at your old pots.
The treble bleed is worth upgrading. I prefer to use a cap and a resistor rather than just a cap. Just google "treble bleed kit" and make one yourself for 50c worth of parts, or use better caps if you like.
I Also like fitting push/pull pots in my RG style guitars to split coil or run the humbuckers in parallel, but you will need 4 wire pickups, and again its been a few years since I did one, but i recall having to re-wire the 5 way selector switch on at least one guitar to get the push/pull working, so it is a bit of research and extra wiring to get that working. The length of where the wiring lugs attach to the push/pull pots can be an issue with them begin to long to fit in the cavity.
Cheap pots are just that, cheap and fail, US$5 pots usually work ok, more expensive pots tend to have a better feel to them.
Hope this info helps