Does anyone know if there are more up to date models of the resistance and capacitance of the human finger/hand? Maybe it does not need to be "up to date" but are there any newer sources, perhaps?

I found a paper on AES that discusses a model, but it is rather dated, 1977. I will only post an excerpt since you have to be a paying member or buy the full paper:

The finger is connected to the rest of the body, which has a capacitance to ground on the order of 10^2 picofarads. The resistance between the finger and the rest of the body is on the order of 10^3 ohms.

 

Your values will depend on your electrode contact area, and electrode type. Which kind of electrodes are you going to use? If you are going to make some report these data must be included. You should use proper medical electrodes. Also you should not measure resistance and capacitance of the human finger/hand? But admittance (look it up in Wiki). I will recommend using a low frequency AC below 500Hz, but not a multiple of the mains frequency. A lock-in amplifier is perfect for this kind of measurement.