Hey Davision,
It sounds like you have some feature requests here, so in order for me to relay this to the developers, could clearly state what features you would like to see implemented?
As for the arrow component as the root component, I am not having troubles getting this to happen. Create a new actor blueprint and add a new ‘Arrow’ component which will be set as the root. What I have also noticed pertaining to the pivot of your objects within the blueprints, after adding my arrow component as the root, I am able to add a cube static mesh under the root and move this within the viewport of my blueprint which then adopts the pivot point of the root component.
Here is an example of what I am referring to:
Root Arrow Component
Edited Pivot
I did get from this post that you would like to have vertex snapping within the blueprint viewport, so if there are other requests you have please let me know
Thank you,