Questions about CGI for a short SCI-FI [Panasonic HC-V770]

Jordan Springs

Hello,
Next week I'm going to shoot a short SCI-FI with the Panasonic HC-V770. The final product will have CGI, mostly adding robots to the shots. We're a small crew, I'm going to do a lot of stuff myself, and so I have many questions for experienced professionals:

1. What settings would be prefered for the Panasonic HC-V770? Focus will be manual, but which shutter/iris/etc settings are best for post?
2. I will have placeholders for the CGI characters. Is there a specific way I ought to shoot the film?
3. Should the placeholders be the same colours as the CGI robots, or should they be green?
4. One of the rooms we'll use is a little dark and we can't light it. The camera shows that it goes to "db" when inside it. Any ideas what will be best to do?

Tips and links to helpful videos will be greatly appreciated. We're shooting at Concordia, Missouri, USA, if anyone's around here and is interested.
Thanks

Terfyn

LED lighting is relatively cheap and very effective. I use a range of Neewer lights from stand alone floods to small camera mounted ones.
My only experience is with greenscreen where real characters are used.