You can remove commend on individual pages through Discussion Module under your post editor. See this for more details http://en.support.wordpress.com/enable-disable-comments/
About your another question. Why you want to remove the Main. If you don’t want main page there then don’t keep Main page as Homepage. Go to “Settings => Readings” and then select “Your latest posts” on Front page displays. Then Go to “Appearance => Theme Options => Homepage Settings => Homepage/Frontpage Settings” and uncheck “Enable Latest Posts”. Once you will do this, you will only have homepage with slider and featured content.