1) First of all, the third "jangle" capacitor is a .0047 microfarad.
2) You can use just about anything for the two regular tone capacitors; RIC uses .047, most other manufacturers' guitar circuits use .022 to not cut as many highs as the .047 does when you roll it down; I prefer a .033 on the neck pickup to get some mellow tones, but not necessarily dark tones as the .047 does when rolled off.
3) 500 kohm pots will get you a tad more brightness; it works well on the full humbucker; it may be too bright on the coil split.
4) Current RIC wiring uses all 330 kohm pots.
5) Remember the 5th knob is not a mix knob in the sense of a pan control, it is an auxillary volume control to the neck pickup to "balance" the output of the bridge pickup when both pickups are selected.
6) Yes, you can wire a push-pull on the 5th knob to wire the guitar however you wish. I have a whole thread on that with my wiring mods on the RIC factory forum:
http://www.rickenbacker.com/forum/viewt ... f=2&t=7928
7) Unfortunately, your wiring diagram, frankly, makes no sense. You do not have symmetry on how the two tone capacitors are wired; your pots are not labeled so we know which you want as volume or tone. Here is the standard 330 wiring diagram so you can adapt it to using HB-1 pickups:
http://www.rickenbacker.com/pdfs/19511.pdf
8 ) A 381 has Ric-O-Sound wiring; your diagram reverts to something more like a 330 with a single output. If you want to retain Ric-O-Sound, here is that factory wiring diagram:
http://www.rickenbacker.com/pdfs/19502.pdf
9) Finally, here is the schematic for an HB-1: red is hot, black and clear are tied together, blue is ground. To get a single coil tap, the push-pull needs to be wired so the black optionally goes to ground when you pull the switch. It is confusing, because every manufacturer of a humbucking 4-wire pickup uses a different color code for the leads.
http://www.rickenbacker.com/pdfs/19521-HB1%20Wiring.pdf