Still getting around to my own article on explaining Steemit simply in fact (elevator spiel) but as to your #1) How would you explain Steemit in a few sentences to your friends? :

"Steemit is a free blog without the ugly intrusive ads, a social network without the drama, and a crypto-currency without the volatility." Then unpacking these statements in paragraph form would be my "article" which I'll probably use as a script for my podcast.

I've also written that "Steemit is to Facebook what Facebook was to MySpace" on my redirect url here (which is my new business card to promote my profile and other sites).