Yes, you can make nice children's books, and in this connection, you can correspond with Satyabhama who is already working on a condensed version of KRSNA book. And you should continue your painting, then with love and devotional practice your pictures will become all attractive because of the bona fide transcendental subject matter. However, in the meantime, you write to say that you have painted Mother Yasoda light blue color. Please let me know where you have received this information. Yasoda and Nanda Maharaja should be colored as Indians are generally of a light brown, tan like wheat.
Regarding Svetadvipa, the information is given in the Brahma Samhita, Svetadvipa, the Abode of Lord Caitanya, is a special portion of the same spiritual planet, Goloka Vrindaban.
I am so pleased to know that you are carefully caring for your Deities and that you chant before Them always when at home. So the Lord is very kind upon His sincere devotees, and He will provide more and more opportunities for such a sincere devotee as you to advance in serving and remembering Him at all times.