Murder Gamemode help

Hello, I have recently just started a murder server and I was wondering how I can allow my admins to have phys guns.

Not only do I want my admins to have phys guns, but I also want to be able to spawn props in to edit how the map looks. Is there a way to do this? How do I make murder a game mode I can customize to create it more custom to my liking? (I need to phys gun things around).