Elie, I thoroughly enjoyed my treatment with with Dr. De Smet, and so should you.
What to take? Comfortable loose clothing and a swimming costume.
You have about half an hour physio in the morning, and then the nurse will change your wound. In the afternoon, you have half and hour to an hour of hydrotherapy. Don't be late for either. Apart from that your time is free.
A couple of good books helps a lot. I had a few spare and left them at the villa. I took my laptop too.
You will be resting much of the time, but not necessarily in bed.
It is reassuring to have your spouse stay with you, some people bought their whole family. I would not recommend your husband rents a car, getting in and out of, and riding in a car is not comfortable soon after surgery. Instead, you might want to take lots of short walks. If you feel up to it after a couple of days, you could take a tram or taxi into the old town and walk around there.
Most of your time will be relaxing, enjoying the company of the other patients, and physio and hydrotherapy.
The time at the villa should be a good experience. As for the two days you are in hospital, look at this thread that I wrote the day I came out
http://surfacehippy.info/hiptalk/index.php?topic=1987.0 .
D.