Is there any way to copy and paste an entire Black Ops 3 multiplayer or zombies map into radiant? Any tips on how to do so would be greatly appreciated.

The davs compile the maps and you download the compiled map.  You cannot edit them (from what I've heard) unless you have their uncompiled map files, which is impossible unless they give them to you like they did with the Giant and Combine.  I hope treyarch gives us the rest of the game's maps for the final build though.  Then we can improve what they messed up with on certain maps and easily make MP maps zombies and vice versa (like we've already seen with those 2 maps).