You will need to have the NPC wand to spawn new villagers or you can clone existing villagers with the clone tool and spawn them into your structures. You won’t be able to customize the cloned villagers unless you created them yourself first but you can drop them in wherever you like.
Editing the perks of your NPC is very easy in a simple GUI that explains the perks in separate tabs. Here you can edit the health level of them to what their purpose is. You can make them simple traders or armed guards or anything in between. The sky is pretty much the limit but above all they work for you now.
Once you’ve got your NPCs setup you can even add quests to the game. Control what your NPC is wanting you to do or find and set the rewards upon completion. This adds a new layer of Minecraft becoming a true RPG. Create a world for you and your friends, load it up with villagers and tradesman, and have an adventure while also building experience.