I'm going to be using a mix of RBC and MMF for the first time. I'm also going to be using an edible image on top. I'm having a slight freak out, I always do this when trying something new 
Can I add coloring to the RBC/MMF mix?
Is it ok to use the edible image on top of the RBC/MMF mix? Can I package the cookies individually after applying the image or do they need to dry over night?
Any help would be greatly appreciated!
I make cookies with MMF all the time and use royal icing to accent it. I also use the edible images. You can color both with no ill effects. When you apply the edible image let it dry overnight before you package them. I do not recommend buttercream because it does not dry stiff and it will get squashed once you package the cookies. Hope this helps. 
I am not sure what you mean by a MMF/RBC mix. Do you mix the two together or use the RBC to apply to MMF for accents such as writing or borders? If you are going to use RBC for accents such as writing then no I do not recommend that you use it. Use royal instead. It will dry stiff and you can stack your cookies and package them with no damage. Hope this helps.
This is the recipe I was planning on using
http://cakecentral.com/recipes/7434/marshmallow-rolled-buttercream-for-decorated-cookies
I've always done cakes and now I'm venturing into cookies.
Quote by @%username% on %date%
%body%