How do I toggle on off lights
you change the intensity of the lights, and set intensity to 0 to turn them off. You can create and destroy lights too, but this is not recommended during runtime because they need to be rebuilt into the material shaders. Lighting is very complicated in games.
It depends what you mean. With no experience it'd be difficult to make a fully 3D game that looks/plays like Tiny Tank, making a 3D game is much more complicated than a 2D game, and making 3D graphics also has a steep learning curve.
Let me know what uses you have in mind. If your interest lies in curiosity and simply playing around with new tools it's definitely something that anyone could toy with regardless of their skill level, just don't expect to be making a game until you really get a grasp of what you're doing and how the plugin works. I've provided simple examples for those who got the plugin that outline loading models and setting up a simple scene. Look at the actions/conditions/expressions and make your decision on how difficult those seem. Feel free to ask me any questions as ill be happy to answer.
With that said, the plugin might still be useful if you wish to make 3D backgrounds, menus etc. It's definitely one of the easiest ways to implement 3D stuff into a webpage, i made it and am working on it so that i could more quickly work on 3D stuff through construct, but it's not EASY, i recommend that you could comftorably call yourself an intermediate construct user before using it in its current state. I'm working on updates so that loading models and doing 3D collision testing is more intuitive, but those aren't out yet.