I have a large site with 50,000+ dynamic pages. Even breaking them down into top level subpages, it is increasingly difficult to link them all (eventualy) from the homepage. I am told that it is important to have a link from the homepage in order for the subpage to have pagerank, and yet I see many large sites like imdb.com only have search boxes and no list of links to all their content.
1) How do sites like imdb have rank for their subpages if they are not directly linked from their homepage?
2) I'm assuming sites like imdb submit site maps to google; but at the pace they keep adding, do they have to constantly submit new sitemaps every day?