sachals:
For the 1st issue, Ray Threshold, Ray Depth and Reflection Depth play a role, in the Help files see: User Interface Reference > Dialog Boxes > Detailed CineRender Settings >
General Options (CineRender). Maybe this will also help with the 2nd problem.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David