Lighting is going to be the challenge for large dioramas, because of shadows. Your lighting kit will hopefully include several umbrella-like or soft box shaped reflectors with lights that aim/shine into the underside of the concave surface. This allows the reflected light on the subject to be diffuse and from multiple angles, thus eliminating shadows. You will need several of these. A reflector will also be handy to focus reflected light directly on to a specific spot, ie figures inside of a building. These are usually larger flat round discs that fold/twist to a smaller round shape for storage. They are gold on one side, silver on the other. These can be tripod mounted to aim the light where you want it, or hand held by someone. The two colors will provide warm or cool light, (important for portrait photography). You might research lighting for still life photography to see set ups for shadowless larger scenes.
Most cameras have some range of digital zoom and this provides wide angle for overview shots and telephoto or zoom for close shots. When shopping, test the focusing distance of the zoom, ie if you want to take a close-up of a scene in the middle of your diorama, can you zoom in adequately from the edge of your table and see what you want to take a photo of.
If you want to take your photos another step beyond, consider a camera with aperture /manual override. The “f” stop on a camera is the measurement of depth of field, or what is in focus in front of and in back of what your subject is. Some cameras decide for you what will be in focus, (people standing in front of a landmark, with everything in focus, greater depth of field),but if you want to shorten the depth of field in a photo you will need aperture/manual override. In the example of a scene with lots of clickies in a scene, if you have a greater depth of field, f8 or more lots of clickies will be in focus. If you open up the f stop to f 2.8 or whatever the lowest number is on your camera, only a few clickies will be in focus, and the others behind or in front will be blurred, which gives a nice image isolating a clicks and removes the “clutter” in a photo.
Lastly you should get a camera that can feed the image in real time to your laptop or iPad, rather than use the back of the camera. That will allow you to zoom in on your computer screen to check your focus, lighting etc.
Have fun.