Currently, no option to configure the colors. If you really need it, you may modify the source code. Search ‘$colors’ in tagally-for-wp-function.php file, you will find a color array containing 48 hexadecimal color values. Every two tags in tag cloud use a color value in order. You may modify the array to meet your need.
As for two validation errors, they should be no impact on the use, but we’ll fix them soon.