Thank you so much!
I use watercolors for the background, only instead of using a brush I use a sponge. Then, using one color at a time, I just dab my sponge across the page.
As for the "language", I saw several posts on tumblr about it. Apparently someone deciphered the meaning of the words on North's globe in the movie and then came up with a whole alphabet for whatever made-up language it's supposed to be.