My luggage failed to make the connection from Casablanca to Ouazarzata. This is apparantly quite common and the tour leader was very matter of fact that I would be without my luggage for the first three days and nights of the holiday (half the trip). This included the night in the dessert, meaning I was without my sleeping bag, and I had to borrow blankets from the hotel. On the first morning I had to buy emergency essential toiletries and clothing from the market in Ouazarzata, which was challenging. As predicted, I did get my luggage back at the end of day three. Make sure you carry any essentials in your hand luggage.
The trip is run with a kitty for all water, lunches and dinners for the majority of the trip (Marrakech is the exception), with all meals taken as a group as there don't appear to be opportunities to go out independently. This is appropriate and works well, but it would have been nice to know in advance what to expect.
I was able to buy Morrocan Dirhams in London without any problems prior to the trip - and was grateful for them.
Toilet stops are few and far between - and often involve finding your own convenient bush! That said, most toilets we did find were 'Western' style and usually had toilet paper and hand washing facilities.
The night in the gite was extremely cold and very basic. You do need your sleeping bag there, too, as well as an overnight bag. This is the second night you are without your main luggage (the other being the night at the Bedouin camp in the dessert). Take a good book/pack of cards/something to pass time in the gite between sundown and dinner.