I don’t generally use the drum editor because it’s quite cumbersome and my setups usually vary too much to warrant a map setup. (I wasn’t aware it can output to different VSTis though, so it seems worth a second look. Also the fact that note lengths can now be adjusted is a bonus)
As far as the multi row moving and mapping questions, I couldn’t find an answer either. What I do know is if you click the channel or output column and ctrl/cmd+select an option, it applies the change to the whole map. Not a fix, but might come in handy.
In Cubase 8.5 the drum editor has its own “visibility agent” just like the mixer and project windows though. This allows you to only show lanes that have been mapped or even just those containing events. It helps quite a bit to get rid of clutter.
Strange though that one can select multiple rows and it seems to serve no purpose! Worth looking into.