500k pots will brighten your tone, so if you're after a slightly dull sound out of your bass then that's not the way to go.
0.01µf is 10nf (nanofarrads), if you want something in between this value and no cap then pop a 0.0047µf (4.7nf, sometimes written as 4n7), as that's the value that's closest to the halfway point.
The code for this value of capacitor is 472, though some brands of capacitor have the value printed on.