Some performance questions about polycount

Well, i got some questions about max. visible triangles in a scene.

  1. I know about console command state RHI to show triangle count. Is that the real visible count from both sides of meshes or 1 side only (backface culling) ?

  2. I was reading that 1 mesh with 50k triangles is better than 5x 10k. Is that correct and why? Because i thought, if i got more smaller objects, it could reduce triangle count in the visible area. I created 1 object with arround 30k triangles and if i move the camera arround, the triangle count is still the same ( if i view only the half object i.e. )
    Are the drawing calls more expensive than triangles?

Regards, NJ