There is a Curacao dive guide available on the island, but you can't get it before you get there. Someone will chime in with more info, I'm sure. I got mine from Sunshine and if you are staying in Westpunt, I am sure she or someone from OEW can line one up for you.
There is also "The dive sites of Aruba, Bonaire, and Curacao: Comprehensive Coverage of Diving and Snorkeling by Jack Jackson, but it is about 10 years old. The same book was re-released with a slightly different title a couple years ago, but from what I have heard, it is not updated.
Otherwise, if you search here and take a look at some of the websites for Curacao dive ops and for Sunshine and David's apartment rental, you can get a lot of information.
There is also a drive and dive map available on the island, but it doesn't contain any info about the sites, just their general locations.