Sounds like several questions here, the first is can we use extensionless urls, and the answer is yes for CMS pages, blog posts etc, see the linked article. But you should not use extra segments like /members/ in friendly urls in mojoportal as documented here.
However when you ask about making things like Facebook or blogger it sounds like you intend to let strangers have their own pages and edit content, and mojoPortal is not designed for that for reasons indicated at the bottom of our About page.
Best,
Joe