1. So I see this drop down menu with a bunch of options.

https://i43.tinypic.com/qybkeq.jpg

I usually use Production quality when I render but I wanted to know what all the others do?

2. And I set my AO render colors to white and black but I still see a lot of grain in my renders. i set my samples to 72 and my resolution to 1k square plus 300 resolution but I still see too much noise/grain. Do I just keep cranking my resolution?

Thank you