/ic/ - Artwork/Critique

Need some help/advice on making prints of my work.
1. What sizes/weights are usually used for prints?
2. Paper recommendations?
3. How much should I charge? how much should the price increase/decrease based on the size?
4. How bad is the quality loss for large prints?

Anything else I should know about prints

I've only made prints once before at the campus print shop. It was on basic paper and double the size of printer paper. ~1.00 per page

help meh , i want to starting doing some value grayscale, i have try it a bit , its so freakin hard to blending with manual brush, mine looks like grandpa shit, i always instantly using eastern kind coloring (which usually sai user using),but i doing it in photoshop , can someone give some basic thing that i need to know to doing grayscale?maybe link or something?
picture related , but NOT mine, and i not sure that done by grayscale, sry for asking to much