For a low volume search term with low competition, you might be able to rank highly in SERPs but for a more competitive term, you definitely need more than 3 pages.
focus on optimizing each page on your site for the specific keywords. I would suggest using googles keyword tools to find the best keywords to focus on for each page
Do not inter link the websites, unless they are on different IPs. You could get penalized because you may be considered as link bombing.