Node system black viewport and gpu fails

Hey guys, I am relatively new to cinema and this new node system for redshift makes me a little bit sad, cause everything I know from other programs, somehow works really different or doesnt work at all (base color texture, from substance, in color inout if standard rs material makes the whole model just black without reflections). Do you have any great sources to understand new node system? Also pc is always getting out of GPU and I am not sure what are the best setting to optimize. Sorry for nooby questions, thank you for help!