Definitely a couple of ropes assuming you want to leave your rap rope in place.
Full rack up to #4. I remember placing a 4 (and then bumping it up with me) on The Climb (*** 18). Cool route. I always take doubles just in case but that's just me :) Several routes are multis with trad belays so that always eats a bit of extra gear. You may well also use a bit of gear on the rap anchors - there are bolts at the top in a number of places but not all. Bolts are often set back a fair way from the edge. Take bolt plates from memory.
Probably the biggest thing to be aware of with WCH is the approach. It's a ~1.5 hour walk-in from the main campground in sometimes soft sand or a moderate 4WD adventure (low range, tyres down to 20 PSI in spots, fold your mirrors in). Don't try it in a soft roader as clearance is a problem. We always drive in and camp on the cape near the climbing in which case take all your own camping gear including water. There are a couple of little streams to top up water if you look hard.
It's also worth checking the weather forecast as it can get very very breezy down there and, depending on swell conditions, the bottoms of some pitches will be inaccessible. Not to say you can't climb them, just that you might have to start from a little higher up or else risk getting a soaking.