They are mainly changes in the markup and CSS so the testing would be to check that it's still valid html strict, the layout is correct in the most used browsers, say IE FF Safari Opera?, and the CSS are valid.
Since the list is long and I have only 1 week, I won't have time to do all of it but I'll try to do as much as I can.
We'll discuss this at honchos, but my thinking is to do as much as you can, and after one week we can discuss releasing .lrn 2.4.0 beta1 (assuming we can release core this week!) or spending more time if necessary.
I'm re-ordering assessment portlet for our install, I'll keep in mind to comply with your above points. I'll post my changes on the forums later this week.