Shift-Alt-Click selects a single object but can I now add other objects to be moved with it?
Not yet. No doubt it will appear in the next turn through editing improvements.
I have trouble using the right click drag short-cut on my laptop and tablet.
That's a shame. The right-click-and-drag to zoom box may be one of the most popular GUI innovations in 9. It seems that for almost everyone it takes just a moment to get permanently addicted to left click and drag to pan and right click and drag to zoom box. Add the wheel and it has to be one of the most fluid and easy navigation set ups most people have seen in any application, ever. "Most people" and "almost everyone" of course is not the same thing as "everyone."
I guess the analogy for tablets would be gestures. For laptops if you have an icky pointing device I suppose for now the answer is practice (click and hold down the right button with your thumb while you work the touchpad or trackpoint button with your index finger).
Adding a dedicated zoom box command, and the dedicated mouse mode that implies, is an unpleasant thing to do because then you can't use it in the middle of other activities, the way you can use the current mouse moves. Example: right now, you can start drawing a polygon and in the middle of doing that do a zoom box to get closer to something and you're still editing OK without any interruption in the flow of that. Do a dedicated command and you lose all that.
but I would also love to see the Select Nothing tool make its debut in Mf9 too (I know the short-cuts but cannot seem to make them flow - perhaps it will come with practice.
Use Edit - Select None or Shift-Ctrl-A or, if everything is selected, Ctrl-I. Like anything, that comes with practice.
The solution if you don't use the product frequently enough to remember shortcuts is to just use Edit - Select None as a reminder. The solution is not to wallpaper the display with a zillion icons the functions of which are not remembered by anyone who does not use the thing frequently.