That's a bit low, that behavior might be normal with that amount of RAM. make sure you're using sleeping tabs and set the time out to minimum which is 5 mins, hopefully that helps edge://settings/system
That's not a lot, I think you're experiencing a bug, if you haven't already, please use the feedback button on Edge to submit a report and explain your issue there. developers will have a chance to review it. press Edge's (...) menu button => Help and feedback => Send feedback
Open Windows task manager, from options select always on top, let it stay on top and then browse in Edge and reproduce the problem. sort processes in task manager by memory usage, see how much memory is being used when you see page refresh in Edge.