A: Yes.  In version 4.5, this can be done by modifying the colouring.xml file located in user configuration area in C:\Users\username\AppData\Roaming\ioGAS. In version 4.4 and older, the colouring.xml file is located in C:\Program files (x86)\ioGAS\data folder (or equivalent 64-bit folder).  The colours are entered as RGB values and the size represents the proportion of the colour ramp assigned to that colour. Open up the colouring.xml file into a text editor such as NotePad or WordPad or even better is Notepad ++ as this colour codes the different xml text making it easier to edit.  Make a copy of one of the other colour ramps and give it a new name and change to the values you want.  See Add Custom Colour Ramp for more information.