I can try to answer 1. I'm guessing you are using Iray. Look on the render tab in the Environment section. By default, Iray sets the Environment Mode to Dome Only or Dome and Scene with a low resolution HDRI on the Dome. The Draw Dome property also defaults to off, so you cannot see the Dome in the render (but you will see it in reflections if you have a hightly reflective object). To render with only scene lights, set the Enviroment Mode to "Scene Only". This will turn off the dome.

Don't be surprised if your scene then renders rather dark. Spot lights are not very bright by default in DAZ compared to the Sun. You can turn up the light intensities or you can adjust the Tone Mapping properties on the render tab. Turning up the ISO will make the scene brighter.

Rather than doing an actual render, you can use NVIDA Iray display mode instead of the default Texture Shaded mode. This will give a preview of lighting and lets you adjust it more quickly. You can do this even if you do not have a Nvida graphics card, although it will be slower.