I would not be concerned with optimizing for internal search. You want to optimize for Google, Bing and Yahoo. The Learn SEO files here on SEOMoz should give you the basics, and you might find it very helpful to use the on page analysis tool to go over the basic onsite optimization factors.
Not sure I have ever used a page number on a site, though I do see sites that use them when they have a string of say, affiliate pages ... a way to answer this question is to ask: how will it help the visitor to my site?