The first question here is on help: "We have a set of doc plugins for our product. How to host them on the net like the one at help.eclipse.org?"
Eclipse ships a class called org.eclipse.help.standalone.Infocenter, which is available in org.eclipse.help.base_{version}
-command start
-port 80
-eclipsehome
Assuming the jar is in the classpath, the command would be:
java org.eclipse.help.standalone.Infocenter -command start -port 80 -eclipsehome /Users/prakashgr/eclipse/