Not sure what Dan uses but I suspect it will not be much different from this.
Offset min 4% rotor diameter ( 1/2" per foot of rotor seems a good figure).
Angle from vertical about 20 deg.
Angle from straight back is not critical, I think Dan uses 45 deg, Hugh I think uses 55 deg, it has some effect on the power produced during furling.
Distance from tail pivot to centre of vane is typically blade length ( 1/2 rotor diameter) I like it longer but with plywood vanes it may not furl early enough if you go too far.
I will leave the area to Dan, I always tend to make mine too small and need the tail at a considerable angle to keep things straight into the wind.( maybe 16% of blade swept area is reasonable)
You can only find the tail moment by experiment but plywood tails normally work about right with boom length about 1 blade radius.
Flux