If those don't cut it I assume by "active" you mean stuff that's being posted on or looked at during your session? The two links above still somewhat give you this functionality. If you have an example of what you want just link it. If it cant be done in SMF by default, I will emulate it to the best of my abilities 
Not exactly.
Basically just a top 10 list of threads with the most recent posts.
For example, when I submit this post, this thread will be bumped to the top of the Suggestions board and would also be at the top of the active topics board. Subsequently if someone later posts on the 360 General discussion board, that post will be at the top of that board and also be at the Active topics list.
The active topics list simply shows (and links to) the top 10 most recent posts/threads regardless of the board.
It is not a critical site feature, it is just something I have seen and use often on other forums.