Background colors for mosaics should be chosen based on how well they contrast with the colors used in figures. For this reason, most mosaic artists will tile their figures first and then choose their background colors by a trial-and-error process of placing tiles on the mosaic backer and just seeing how they look.
The same approach can be used to decide what pattern of placement (andamento) you should use for the background. You look at what you have in the figures in the foreground and choose a background pattern that is compatible.
Many people report having trouble cutting vitreous glass mosaic tile reliably because of the embossed patterns on the back sides, which can interfere with the blades of the mosaic glass cutter, but if you take simple steps to minimize interference and rotation, it can be done.
What I mean by interference is when the blade slips down into a valley between two ridges instead of staying positioned in the desired line of the cut.