Mazurkin -
Riven Earth, Desert Rocks, The Druid, Tyrant, Knight Errant were all concepts done for Guild Wars 2. Riven Earth and The Druid are actually GW1 subjects that we are bringing back in GW2. I slightly re-designed the original vision for the next project. I look at photos of nature to get inspiration for textural treatments. Overall shapes and forms are usually from my head.
It takes me anywhere from a day to a week to do one. Depending if the idea is good or not, or if I have to make more corrections.
The difference varies from artist to artist, but for me it was hard to get use to my hand being in front of my face. And really I still just as fast as I was with the intuos. Also the weird thing too is my posture was way better with the intuos. But mark making is a lot more natural with the cintig.
Setha-
Around 5700x4000 pixels, though this is not a fixed number.