Is there such a built-in shortcut for doing such action pairs? (e.g. accept+move to next, using a single shortcut)
If not, how can I define such a custom shortcut?
This is actually quite easy to do, once you know where to look. (Unfortunately for me I didn't know about this until my thesis was done. Not that I'm bitter or anything.)
1) In MSWord, go to the Tools Menu and then choose "Customize Keyboard"
2) Under "Categories" choose "All Commands" and then look for "AcceptChangesAndAdvance". Select it, then click in the box next to "Press new keyboard shortcut" as shown here:
3) Enter an unused keyboard combination (I chose ⌘ + ⌥ + Y for "Yes I want this change"). Note that the "Assign" button is now activated. Use it. Then click "OK".
That should be all you need to do.
In office 2007 you can set a custom shortkey at "File -> Options -> Customize Ribbon"
There set a nice key, like ctrl-shift-Arrow :)