That was a long, but really good post. I agree with most of what you say, but there are a few things I want to point out:
1. Some people follow basically anyone who follow them. So if you have a lot of follower, it might just means you followed a lot of people (it's the same for reputation sometimes, but fewer people do that, and it could be hard to determine who give you the rep in the first place, so I'll ignore that for now)
2. Sometime people set up an account for sometime but didn't use it. And then one day the person remember that they have an account and starts to post really often. So it can be hard to tell if someone is a long time lurker or just a slow poster
As for how to increase your population on the Shard, there's one thing I want to add
Post in more board, it might help as there are many who only stay in theory discussion, and people who only visit the community section