Hi Lucko, pozdrav and thank you for joining the forum!
Regarding your first question: The Analog Inputs and Outputs have 10 bit read and 8 bit write resolution, you are right. We are currently working on updating our datasheets to also include such information.
Regarding your second question: you can just use analogWrite() function with a value of 0 – 255, we don’t clearly understand why you want to set the resolution as it is fixed by the controller. If you could elaborate more on that part, we’re glad to help.