Double edit: I have answers to my own questions. In case you were as confused as I was, making a new blog post tagged #observationdeck allows you to post on the deck. Someone must share your post to get you off the, er, lesser deck.
Editing your comments is easy, use the triangle. As for b, well. Time will tell, I suppose.
[Is this going to just publish on my profile? How is this new commenting system accessible?
How do you see other people's posts? Also can we not edit our posts now? ]