I think 16GB would be a better choice. If you could put together an affordable storage combo that includes a 256 or 512 GB SSD you’d probably really like it.
I think so, but I’m also aware that there are users on this forum who have models that would bring such a machine to it’s knees. Usually very complex architectural projects. So it ultimately depends on what you intend to do. Your proposed machine should handle a fairly large range of typical Rhino projects.
BTW: you probably should get the fastest and most recent i7 version you can afford.