You can call me
Seph if you like

bit easier on the fingers than introvertebrate
the normal RPM for a bike wheel sized rotor is around 250 - 300 RPM... to get a rotor that size into the thousands of RPM it will have to be very well balanced, light, and streamlined... the spokes may create alot of drag so you may have to work around that.
several big cols will be needed... I can only guess at how many you will need, though I would think about 3 x 750 turn trifilar coils would probably do it... that will probably draw several amps... so, as a guess, lets say it will draw 3 amps you will need a 60 amp hour battery to run it efficiently (at 12v).
This is the fastest BIG ssg I have seen
http://www.youtube.com/watch?v=_CivUKkFdx0
it runs on 63volts and draws about 0.56 amps (about 35 watts, equivellant to 12v at 3 amps)
You won't need to use larger magnet wire since you will be using several wires in parellel.
Though it isn't really a good idea to throw yourself in at the deep end... the ssg has alot of subtleties that need to be learned through experience. For high performance (I'm not talking about RPM) you need to have a combination of many factors just right. This is why it is a good idea to start with a smaller model so you can experiment and change things easily... if you rush in a build a huge replication you will find it harder (and more expensive) to change things later.
Don't rush it

and bigger isn't always better anyway! The main advantage of having a big rotor is that you can add more coils around it. A second advantage is that it will spin at a LOWER rpm! This means less air resistance and less friction on the bearings so it is more efficient!
It isn't about RPM... more importantly its about pulses per amp per minute.