Not silly!
It's kinda hard to imagine what NB will be like before you actually try it.
So for me, when I pump, my breasts slowly start to expand in the domes as I go. The longer I pump, the more they expand/swell (but I almost never go longer than an hour). When I take the domes off, my breasts remain swollen, like they were with the domes on. The swelling goes down slowly; for me most of it stays for the first hour or so, then after a couple hours I think they're about back to normal, but a little fuller still.
As for positioning, I don't have a whole lot to work with yet as I'm still a 32A/30B, so I just put the domes on any way that they will get suction. Some days it looks like my nipples are facing one way and another the next, but I really don't pay all that much attention to it. I would imagine with larger breasts it would be easier to actually try to position them a certain way as you may have an easier time getting suction.
Good luck and welcome to the world of NB!