Not sure how long the lounge is open, for us it's "all day" (except for an hour when they convert it from breakfast to lounge)
Snacks change, so can't answer that. If you search on line you'll find pictures, but like I said, they've drastically changed them a little over a year ago.
Golden Forest rooms have a fridge, normal rooms don't
You can upgrade your dining plan, but it needs to done at least 3 days before you arrive.