No worries! I surely could have done a better job explaining it.
That’s a good idea. Two peers behind NAT or on the same box would get the same ID, but that’s probably not enough of an issue to introduce a separate node ID.
That seems reasonable, as long as a single block time gives adequate opportunities to aggregate transactions.
An alternative might be to immediately fluff a transaction if you are stemmed it twice. I.e. on first receipt of a stem transaction you stem it, but if you receive it again you’re probably in a cycle, so you fluff it. I don’t really have any reason to believe that this is better or worse than using probability though.