I noticed that the FR645 has not been added to the UXGuide appendices yet. Can anyone tell me if the FR645 screen is basically the same as one of the older devices?
In what way? The fr645 and fr645m are both 240x240 round screens with support for 64 colors. The data field layouts are similar to that of many other 240x240 devices like the fr935.
You can get details about devices by looking at ${SDKROOT}/bin/devices.xml.