On which threads ought to exist and whether we need to be completely granular, I think the guideline there is simple: we'll know when it's necessary. If there's not that much difference in products in a family and separate threads aren't necessary, let's not fire them up. But if feels like they are, let's.
Common sense should take care of it. Say we miss creating one that should exist and need to patch that up, we can always seed a new thread from existing posts in a thread, etc. Or if we go too granular and one thread is bare, we can fold it into one of the others. We've got the tools to just roll with it.
On the reopening + republishing of rules date, including inviting new moderators to the fold, we'll punt to next weekend. I setup a new mods only forum with some threads to discuss some details last weekend, and hoped to get to the feedback today and tomorrow and maybe reopen on Sunday, but there's not been enough discussion yet, especially on the proposed new mods front.
Some names have been put forward, and there's still time to put yourself (or someone else!) forward too now if you want. So if you fancy helping out, or think someone else might like, just let me know.