If you change your development status no event is sent to your followers. If you write a devlog post then it will be published in all of your followers' feeds. At the moment we don't sent out email notification for devlog posts, but it's something we'll be adding sometime in the future.
We don't let developers directly email followers. You can however email anyone who has bought one of your products.
Instead of emailing followers we plan to have a digest email about things that show up in your feed if you haven't viewed it in a while. Another feature we've been considering is a mailing list for developers where people can sign up with the intent of being emailed.