Hi RoninGT, good to see you here:
I dont use Photoshop, but I think your fist issue may have something to do with your tool settings not allowing 100% full color placement.. like its trying to blend the color transitions, rather than fill in pure color.
As to the other map sizes, Dragon wont do that 100% By use of Dragon, you would have to draw a map on your typical 6144x4096 size bmp, in an area that is relative to another map size.. then after rendering into a map0.mul, you would have to use another tool (UO Copy,etc) to copy that section of the map0.mul over to another map file, like map2 or map3.
Dragon will generate other sized maps with no trouble, but DragonSP only supports creating statics0 set. So you would not be able to generate statics files to any other sized map.
There is another alternative, and that would be using the new Map Generator. You can find some info on it within these forums, but more so on
http://worldmaker.ryandor.com
While the transition scripts are still in progress to complete, it is still completely functional as it is. To give you the basics, it uses a terrain and altitude image to generate your map, while still using the 8 bit color palette like Dragon.