Every time I've upload a document with colour, or used the "highlighter" tool, it shows up as greyscale on the tablet's display and shows up in colour if I download it to the computer as a PDF. What do you mean by "nor does it support color (grayscale) schemes"?
As for creating custom templates ... you can make templates for whatever you like. This page has most of the details, including a few different ways to upload templates into your tablet.