Not much. Most was prior to the update.
I have no idea. :0)
IDK, but I would assume there's a server wide variable that controls that.
Probably. I have gone days on end collecting, and consistently (regardless of fog activity), every other day, venom and tears spawn. I think the variables for venom and tears are independent of each other (Not sure) as I think you can get venom one day, and tears the next. As I said, I haven't tested much, so I could be wrong.
I believe this is correct, but as I (try to) freeze all the snowmoors' nests in one day, I haven't experienced Sierepica's position.