When I read your response I thought of the first time I went to a casino. It was easy to enter. Entertaining inside. Nobody asked me for money--as a matter of fact, they offered me free chits to "try" their slot machines. I could have stayed all day and never gambled a penny. Or I could have played the nickle slots. But after a while, I wanted to join in. Looked like fun. It was fun. And at the casino, they literally just took my money :))
Here there's an almost Pavlovian reward mechanism in operation (reminds me, in a way, of the slots). Post an article--wait for the response. The money is in pennies, so obviously that's only part of the reward. When you get a big payout it's like 777. And this is real money, that you can earn by putting in real effort. A fun time, plus profit. There's no downside--unless you buy more Steem than you can afford to lose.
I think your idea of free 'guest' privileges is perfect. Let people have fun. Doesn't cost them anything, but of course they don't get financial rewards as guests. Once they are comfortable, once they see that there is nothing to fear here and it's fun (believe me, I'm having fun on Steemit), they'll want to become 'vested'.
And your discussion of the "keys" is perfect. I'm afraid to use Steemconnect and any of the other applications, because frankly I don't understand how it can be safe to share my keys. It's very complicated if you're not (and I am not) technically savvy.