Like most of the people have already said, you are going to want to incorporate your keywords into the title, and other elements of your page.
I'm not an seo expert, but I think that you should start a blog because you don't have a lot of text content on your content page; so you may want to use the blog to produce content to feed the search engines, and as an entry point to your main site. (you could even use it as a selling point)
I'm not sure exactly how it will affect your rankings if you host the blog on your site vs a separate domain, but I'm sure that there are arguments for, and against, both options.
You may also want to do some research on other keywords to see if you can find some long tails that can bring in a few extra clicks for a low cost.
Look for ones that are bringing in a few hundred clicks daily, and make sure to register a domain with that keyword in it. This will be more time consuming, but cheaper than using adwords.
For instance, I found adultcontentprovider.org to be unregistered; if you do some research to see how many clicks it is getting, it could be worth registering.
http://www.seomoz.org/blog/its-a-fee...rdrich-domains
You should check out the SeoMoz site if you haven't already, and you may also want to buy a book on seo; if you have time to read it. Jennifer Grappone's SEO: An hour a day has a few tips related to adult sites.
Also, here is a tool you can use to check backlinks:
http://www.backlinkwatch.com/