To download the image, just right click it and chose save as.
When you download the image you will get a 1600x1600px image.
You most likely can! The maps created are shared under the license listed below. Just remember to credit with a link back to this site :)
Hopefully! Unfortunately my time is limited at the moment, but if you have any great idears, feel free to message me on the NPCbase facebook page: https://www.facebook.com/NPCbase/
Map textures made by Gogots over at: https://www.deviantart.com/gogots