There are two versions of the Maroc topo mapping....one has the full topographical overlay, the other just the pistes, roads and tracks.
The full topo one can get quite confusing to look at on some GPS units at some zoom levels , and it can be very easy to confuse/lose a track against a contour line.....so in some cases, it's actually better to load up just the basic version.....We use the full topo one on all our GPS units 'cos a) we're very used to using them and b) 'cos I've set up the units to make them visually clearer (you'd need a zumo guru to help you with yours I'm afraid)
Next- the tops maps are actually just overlays, so appreciate before you expect too much of them that although you'll be able to see where you are you can't use them for routing, unless you have a PC and set up a route as a series of waypoints.(or spend a long time adding WP's on the screen itself which is a major PITA)
The easiest (but not the only) way of getting the mapping onto the unit is by downloading Olaf's executable file and double click it.....then open up mapsource and you should find that the little box in the menu bar that shows what mapping is being shown has now become a drop down box that you can use to select whatever map products you have installed, including (after using the .exe file) the Maroc topo maps.
I can't help on loading the maps I'm afraid- I've never got too involved in the ZUMO, but as you say, there are a lot of units (QUEST, RINO etc) where you have to select all the maps (possibly switching between sets using the drop down box I mentioned above) and then upload ALL of them again, as it over-writes the existing map set- I don't know the procedure for the Zumo though so that's a question for somebody else
Have a play with both options (full topo or just road) and see which you can use best- there are hundreds of miles of pistes that aren't on the overlays so sometimes having the contour lines can help you make edumacated guesses as to where a piste goes (I.e it wont go down cliffs etc so you can guess which way a piste is going to veer around geographical features)) so that's another reason I prefer to have the full topo version installed, but on a tour with a lead rider, To be honest it may be better to just have the road /track version installed- you shouldn't actually
need anything else
Find out if you're going to have access to a PC on the trip Geoff.....if you are, you may need to take along your Card reader/USB cables if you want to be able to upload their route info to your machine.
HTH
Bill