According to the Aero-works manual the covering is Ultracote. The manual also identifies the specific colors used. Mixing Monokote & Ultracote will work but the colors will not match.

Not sure from your post whether you are going to "repair" the existing covering or strip the covering and start over. If repairing then use the matching Ultracote colors and make sure that the film covering the repaired area overlaps the film towards the rear of the aircraft. Lift the edges of the existing film towards the front of the aircraft and slide the new film under the film just lifted. This will ensure that the glow slime & wind will flow over the seam rather than try to get under and lift the seam.

You asked about programs. I use Microsoft's Visio. It allows me to create a page size large enough for the entire plane (side or top) to fit within the scope of the page. After I create trim panels I can easily determine the size (in inches or cm - your choice) of the covering. If you have access to a plotter a pattern can be printed. Rumors have it (I just haven't used their services yet) that some sign shops can convert jpg images or file formats like Corel Draw into the format that their cutters use to cut out images.

The picture was created using Visio. It's a Bridi Killer Chaos 60 that I'm building. Iincluded all of the structural components just in case I plan to use transparent covering. This way I can apply a transparency percentage to the fill color to better represent the final result.