There is much info on this very topic in the forums. Do a quick search all most of your questions will be answered!
There are 2 versions of the 20V, silver top and black top. Bill Sherwoods page give a run down on both - http://www.billzilla.org
It comes down to if you want power or streetability (as far as i know). The 20V will give a nice streetable car, with more than enough poke for fun in the hills (i'm in Adelaide too) The GZE or GTE (more money, but good from what i'm told) will give you maximum power and torque! Go for the engine that best suits what you intend to do with hte car.
As you will be putting an FWD engine into a RWD car, all the conversions will be difficult. Again, lots of info in the forums about what to do there.
JMS. I dont know much about then, so i wont comment as i wouldnt want to misslead.