You will love Moroccan House hotel, I loved it so much Im going back in a week, as Tim said, a lot of the info is up there for you.
I went in the beginning of Feb and it was T Shirt weather all day and light jacket in evening, but weather there is quite unpredictable so just plan ahead and have a look on sites nearer the time, such as wunderground etc.
Change money at the airport or at the hotel, rates are the same anywhere.
Restaurants are cheap, but when in Marrakech, you should check out the street food in the square at night, one of the best experiences ever, food is very cheap, around a fiver each for a salad, drink, meats, chips, olives, etc, you will be full up!
Meshwi in pitta (lamb) very yum - is about 3-4 pounds (when I was there in April this year - Prices may change seasonally). restaurants and cafes seem pretty cheap generally, but some of the hotels cost a little more and can be a little expensive.