If you want to do some of the long multi pitch routes at Freycinet or Mt Wellington, I would definatly bring the #4, and would bring the #5 if you had spare room.
If your looking at single pitch routes, you'll find plenty to do that wont require the #4 or #5. (I would still bring the #4).
If you have bolt plates I would bring 1 or 2. There are some great single pitch routes (No Turn Unstoned on Whitewater Wall and Beamans Route Direct on Harliquin Wall) that have each have one carrot. Of course your brand of bolt plate probably will not end up fitting (mine never seem to), so you'll end up slinging the bolt head with a wire anyway.
From memory, Rysv Rydge mostly tales wires and hexes. Because its conglomorate (smooth river pebbles cemented together) cams dont seem to work very well. If you get nervous abseiling on various bits of tape that other people have placed, you might want to take 6 to 8 metres of tape and a knife so that you can add to the raps on the way down.