Hi
I'm hoping to get advice on how to mount security camera junction boxes to hardiflex eaves on steel framing for a recently built house. Below is from the plan for my house:

Picture of the junction box:

The two things I'm unsure about are:
- Should I screw at least one fastener to the steel framing? If so, what fastener should I use?
- For the other mounting points (total of four, three if one is fastened to the steel framing), can I use the screws and anchors supplied with the junction boxes? I don't know how to tell what material they are suitable for... Below is a picture of a supplied screw and anchor.

Thanks!