Go with the flow.
You get back what you put out...so make a point to talk/gesticulate with the camellers and leader. I loved the fact that we were led by bedouins rather than a health and safety obsessed 'tour leader'!
Responsibly hydrate (2L plus a day in an easy access pipe connected water bladder the best) and request rest stops as you require.
If you don't like sand in every nook and cranny- don't go!
Engage with the camellers and help out-after all it's team work and will create a brilliant bond between you, your fellow travellers and the Bedouins.
Feet, feet, feet. 99% of the team will get blisters, even in the most worn out, broken in walking boots. Everyone will have their own preference (but how do you know until you've walked 25kms in powder soft sand in 30+ degree heat?) but I would suggest taking walking boots, trainers and sandals and seeing which work best for you. My top tip..wear 'pop socks' under normal walking socks with trainers..worked for me..I was lucky.,not one blister.
It's hard work, but very rewarding. I'd grade it as Moderate plus, because even though the terrain is flat to undulating, the heat and the powder fine sand make it arduous at times. And don't neglect the fact that it's not all down to physical endurance, mental endurance is just as important. But I can defo say you'll be dead proud of yourself and your fellow walkers by the end!
I didn't pay for a tent, but as chance would have it there were plenty going free so when offered one I jumped at the chance. And yes, they have no zips (sand and zips don't mix) but instead ingenious looped string and metal eyelets worked a treat for privacy. As for the sand...a well placed camel blanket over the door/vents soon stops any coming in. The communal Bedouin tent is a cracking option but a tent offers you a wee moment to yourself to absorb the peacefulness of the Sahara and change/wash in private.
Although I would recommend sleeping outside of any tent. The only time I slept under canvas was after awaking to find that the strong wind had shifted sand around my sleeping bag cocoon until I resembled a dune!