What do these instruments do?
For the panel image that you provided, I should be able to identify all major instruments:



A: Magnetic Compass - Pretty self explanatory. Note that in the real aircraft, A and K may have been switched.

B: Vertical Speed Indicator (VSI) - Indicates vertical speed, either up or down, in feet per minute.

C: Engine Tachometer - Indicates engine revolutions per minute (RPM)

D: Sensitive Altimeter - Indicates feet above Mean Sea Level (MSL). Adjustable for atmospheric pressure via Kollsman knob.

E: Air Speed Indicator - Measures indicated air speed, most likely given in MPH for this vintage aircraft.

F: Artificial Horizon - Gyro instrument giving an indication of an artificial horizon; shows pitch and bank variations.

G: Amp and Volt Meter - Amps are indicated on the left, volts on the right.

H: Oil Pressure and Temperature Gauge - Oil pressure is indicated on the left, in PSI, and Temperature is indicated on the right, in °C.

I: Clock - Probably an "8-Day", spring driven, hand wound device.

J: Magneto Switch - Control for ignition systems. This control only shows three detents. There should probably be four detents: Off, L, R, and Both (L and R refer to Left and Right magnetos).

K: Directional Gyro with Inclinometer - The bottom part is the Inclinometer (ball), indicates coordination and skid or slip. The top part is the Directional Gyro. Note that in the real aircraft, K and A may have been switched. 

The inscription reading "NR2100" is indeed the aircraft registration, typically used as part of the aircraft callsign.

The knob below A is likely used to set the gyro compass (K) that should be in that location.

The knob below F is likely to adjust the pitch indication on the artificial horizon (F).

The red knob between F and E is probably meant to be a knob to cage the artificial horizon (F) and should actually be placed in the location of the screw directly above and left of that red knob. See the Bee Gee Z panel I linked to below.

The knob between E and D is probably meant to be a larger knob that might be part of a pull control. I have no real idea of what it is, but my guesses would start with carb heat, primer, starter engagement pull knob. Could be many other possible functions.

Reference the photos in this album by Roger Ritter depicting a Bee Gee Model Z. I understand that it is not the same model that you are looking for, but the cockpit layout is very similar, and should be informative. His photos helped me confirm the identification of the gauges in the panel image you provided. Photo album linked only, due to image copyrights.