Yes, you can delete it and add it from the prefab list. Highlight the object and press "Backspace" on your keyboard. This works for everything I believe.
I'm not sure what you mean by blurred, perhaps it's your shadows?
You simply put the files in your prefabs folder. For example mine is located here:
D:\SteamLibrary\steamapps\common\Call of Duty Black Ops III\map_source\_prefabs
Inside of this location, I have a folder called "Kaizokuroof" and I put my prefabs in there.
Yes, it seems you might have forgot to put in dog spawners, they are seperate to zombie spawners. You can find details on how to add/remove dogs here:
https://confluence.ugx-mods.com/display/UGXMODS/BO3+%7C+Adding+Dog+Spawners+or+Disabling+Dog+RoundsHope this helps.