Simple Mosfet Regulator

[Daniel(Del)]

Hi all!

I'm going to buy a new Sony HU and before installing it on the car, I'd like to test it.
So I came up with the following circuits on Multisim, so that I can use a 90W Notebook PSU to feed it. The choice of a Mosfet pass transistor is mainly because I have it already. I have a few questions though:

1) Is 10uF enough for C1? How can I calculate it more precisely?
2) Is 470R enough for gate stopper resistor (R3)?
3) Should gate protection zener (D2) be connected to Gate and Source (pic 1) or to R3 and source (pic 2)?
4) I have 4x4700uf Elnas. Is better to place them before, after, or some before and some after the regulator? I can also buy other values if needed.
5) Finally, what would be the differences of this type of regulator and shunt regulators (like Salas') in the final result?

Thanks in advance
Daniel