A1. You don't say which version of Lightroom you are using, but in the current version at time of writing (CC 2015.10) what you describe in Q1 always happens by default. If I select either a single image or multiple images and create virtual copies, each virtual copy is stacked with its master. In fact, as far as I can remember that's always been the case. Have I maybe misunderstood your question?

A2. If you only have one virtual copy of each photo, this is quite simple:

1. In the Grid module, enable the Attribute filter (from the Library Filter bar at the top) and next to Kind click the Virtual Copy icon (the middle one of the three).
2. Use either Ctrl + A to select all your virtual copies, or the usual multi-select methods to select just the ones you want (Ctrl + click, Shift + click).
3. Turn the Virtual Copy filter back off. You will now see all photos again (masters and virtual copies) but with only the virtual copies selected.
4. Now hit Shift + [ (or from the menu, Photo > Stacking > Move Up In Stack) to move all the virtual copies to the top of their stacks.

For some reason, the more obvious function Move To Top Of Stack (Shift + S) doesn't work on this sort of multi-selection: it only affects the highlighted/actively selected image.

If you've got multiple virtual copies of each image then the Move Up In Stack bit will still work, it just gets harder to only select the last virtual copy of each image.