1. I would advise posting to it just to give your potential castmates some warning. If they don't see it someone else will probably go find them for you, people are nice like that.

2. It's kind of like asking someone out on a date. It's totally fine if such-and-such isn't what you're looking for right now, or you need to do some soul searching before you commit, and you have the option of saying "hey let's do a thread or two together and see how it goes!" Except as far as I know we don't have anyone who will stalk you and try to guilt you into a serious relationship.