Well done, Keyplus. You know taking my advice always makes sense. ;o)
When you get there you'll find loads and loads of taxi drivers outside the airport holding boards with names. You'll need to look very carefully for yours - there are so many. If you've booked with the company I recommended, your man will probably be standing somewhere to your left. You can change money in the airport so you have something to tip your driver with and hopefully enough to last the duration of your visit. Changing money is not cheap in Morocco so it's best to do it all in one hit if you can. Depending on the restaurants you use you can spend a little or a lot, but you can check prices on-line to gauge your approximate expected spend. Marrakech is a vibrant, busy, bustling city, and far more modern than you might expect. Do let me know how you get on. I hope you have a nice time.