The “Active Topics” in the sidebar on the right always shows the most recent topics (the most recent at the top). Anytime a reply is posted to a topic, the topic with the most recent reply makes it float to the top of that list as well. There’s also discussion about wanting to add that list (the most recent topics) to the homepage, which is in the works.
What also might help you navigate the forums is the “Read/new” marker to the left of each forum and topic. Forums and topics that you haven’t read yet (you have to be logged in for this) have a dark blue bar next to them which should make them easy to spot if you’re scanning that list.
As you’re editing your topics/replies, besides the font being a little different, it looks just like it will when it’s posted. You can also edit your topic/reply even after you’ve submitted it (there’s an “edit” link at the top of all topics and replies that you’ve submitted).
Let me know if that addresses what you need.