Plus I still heavily recommend https://learnopengl.com/ for learning basic abstracts of how things are done when it comes to rendering, camera, coordinates, shaders and lighting. I believe Defold is capable of great 3D, but because of its focus on 2D and Web and mobile games, most of the features that are out of the box in other engines are not yet implemented here - but thanks to this, parodixcally, it is in alignment with what you want - full control over it 
The path is just a little bit longer, but learning all this will be fruitful for you regardless of what tools you will be using in the future 
Smooth camera movement - if you use camera component attached to game object - make it a separate object, not a player object - then animate / linearly interpolate (search lerp) it to follow player after. I do it like this even for 2D games.
Skybox - is cubemap component in Defold not what you think about?
Normal maps - again, I do it for 2D, but I did it basing on Learn OpenGL explanation on Forward Lighting (Basic Lighting), here’s the process using which I plan to convert into video tutorial soon