Oy dragon-soul! To answer your question about how often to post, for me, I think one or maybe two posts are enough. That way you can see how everyone else is reacting in that moment and can respond to direct questions and stuff like that.
I think in general you don't want to make too many posts because we will want to see how our GM's NPCs respond or react to the things we do and say, and how the GM narrates the outcomes of what we've chosen to do. If we move too far ahead, things and timelines can get jumbled.
For instance, Cho'Ra has asked to heal the wounded woman, Thren has asked if we would like to go grab a bite before saving the day, and Dane has asked the the woman if she would like to join us. We won't know how the woman reacts until Giddy makes his posts. Then we can respond to what she chooses to do and any information she chooses to offer us and interact with each other and move on from there.
Other people may have a different opinion, but so far that is what I have seen to be effective in this form of story-telling and play-by-post RPGing.