Some really good ideas (not sure easy/hard they'd be to implement, but I'd happy use a follower graph and would selfishly love to be able to afford a territory).

One idea that kind of combines #1 and #2: A territory graph as well. I subscribe to three territories, but there are about 15-20 that are ones I'm a lot more likely to interact with, and if I had a feed of all of those posts separate from the firehose, that would be a great landing page.

(The question, I guess, is whether that would reduce interaction on the main page; it wouldn't for me, because I'd start at the territory graph and then go to the larger feed, but others may react differently.)