1. I feel the same, it's not enough activity to keep coming back to it. Being greeted by a grid of screenshots / gifs / trailers, with new ones frequently added, is going to keep me checking back in.
2. Yes. Easily being able to follow projects is key I think. Often when I see a screenshot of a game I find interesting e.g. on twitter, I want a way to be notified when that game is released - currently there is no way except go into the developer homepage and hope they have a mailing list (not a very smooth process and often they don't have one).
3. Absolutely.
4. I'm not sure. The way I imagine it, is that it can be configured on a project to project basis, because for some projects I'm only interested in the milestones (releases etc) other projects I want to see every content being put up.. comments might be too granular for me personally but it could be an option if people want to follow every little things said.