One month ago I submitted to dmoz and google/msn, etc. my website. Now I added some important subdomains and subdirectories (a site.com/community, a games.site.com portal, etc.). Should I submit all them to search engines and directories, or is it sufficient the main site which is already submitted?
Don't worry about submitting anything to the search engines, it's a waste of time. No need to submit the new subdivisions of your site to directories. Introducing subdirectories is a mistake from the SEO point of view: Google treats subdirectories as separate sites, so they don't help your main site at all. I suggest you create subdirectories for them on the site and 301-redirect the subdomains to the corresponding subdirectories. Then create a new XML sitemap (you can use http://www.xml-sitemaps.com) and submit the sitemap to Google in your Webmaster Tools.