If you want to work on components / templates etc then you need to
modify the ui.apps project. The ui.content project mostly contains the
html pages, DAM content etc.As far as auto completion in jsp's is
concerned, you should get all the info you need from the below
link,http://docs.adobe.com/docs/en/aem/6-0/develop/how-tos/howto-projects-eclipse.html