It depends if you get the standard or the premium model. Standard has cloth, premium has leather as sides, and another kind of leather in the middle (sorry that don't know the name of it).
Yeah, there are quite a few in sydney. They are not that rare. There is this girl at uni driving exactly the same as mine. However, havent really seen them otherwise except for sale yards when searching for it.
I've got one. Think for any modifications really, you have to look at what the americans are doing (can't read jap). Check out Infinity G35 forums. I personally like www.g35driver.com
I have a V35 coupe and I love it. The pics are not the V35 model. Well, not the current one anyways. Only thing that is a problem right now is the JDM navigation/computer menu system. However, the car itself makes up for it.