There are many drawing methods in CAD drawing, and different regions have their own set of drawing references, so the best way is to match it with text description, which can clearly show what it is.

Part of this circle and the cross in the middle will appear in the form of lights (chandeliers), and may also represent pipes or something. It depends on the mark in the figure. But we usually use it to represent chandeliers.

I hope it helps you! Hope to adopt

It's hard to judge. Look at the whole picture and see if there are any legends. I still think your painting is incomplete. I don't know if it was deleted or hidden for display.