Garmin is king in Africa
By far the best GPS in Africa and best backup and aftersales service.
I use a Zumo 550 and before I upgraded a 276C.
I find the Zumo to be the best ever GPS for bike and 4x4
GPS updates
the best would be to go to www.garmin.com and see what maps is available for you and then proceed to the udates and downloads page. Download the webupdater application, install. plug your gps in your pc and run webupdater. All very easy.
We also have just a red reflector in South Africa but I also would like to change it to a light. I will keep on eye on this to see if there is a solution