Hello summerdays,
I am from Tunisia but currently living in USA. Regarding the time of your landing you will not find any "louages" or public buses running during that time. So I think you should rent a car just for that day. You may also stay at the airport until 4.00 AM and then take a taxi ( about $5 maximum) to "Station Bab Aliwa" where the louage cars will be waiting for passengers to Hammamet and others destinations. The louage ride should not be more than $6/person. The bus station is on the other side of the road, in case you choose to take a bus instead.
Regarding the noddy train, I haven't had the chance to take it but I do believe that it starts from the old "medina" or castle in Hammamet and go around few blocks than it heads toward the resort/complex of Yasmine Hammamet . Once there, I think that it stops in front of few hotels and the marina, then heads back toward Hammamet/Medina. It shouldn't be over $4/person. If you are planning trips to the capital city or Sousse, the train is a good choice, but you will have to take a taxi from your hotel to the train station in "Bir Bouragba" the taxi ride shouldn't be more than $3 and the train ride should be around $10 to Sousse and about $8 to Tunis. ( In Tunis the train station is about 3 blocks east of Habib Bourguiba avenue, which is the heart of the city.) Once in Tunis the capital ( you better be there no later than 9 AM) you should defintely visit the Bardo museum. You can either take subway #4 (from the station adjacent to the train station) which costs about $0.6/person but it does not stop exactly next to the museum, or actually take a Taxi from the train station to the museum, and it shouldn't be more than $5.
after that you should go back to the downtown area to visit the old 13th century Medina of tunis and its souks. try to grab s.thing to eat while at the avenue Habib Bourguiba. than head north toward the TGM station (about 1/2 Km anorth of the big clock monument. This electric train will take to the northern suburb village of Sidid Bou Said. It is about $0.75/person. once there you should visit the cafe "Sidi chabaane" which is locted on the edge of the cliff overlooking the Golf of Tunis.
Regarding activities to do, I personnally enjoyed going to the beach all day than around 6 PM I usually go to have a cup of tea and smoke a "shisha" (water pipe) at cafe "Sidi Bouhdid" which is located at the foot of the southern wall of the old city/Medina overlooking the sea and you will certainly enjoy the magnificient sunset. (it gets very crowded around 8 PM). About 100 yards north of the cafe place there are few bars and restaurants. I personnally enjoy sitting on the roof top of "Le Berber" bar to enjoy some beer and pizza. Or you can attend any of the free shows/music held almost every night at the "new" Medina at Yasmine Hammamet where you will be staying actually. I heard also that some hotels in Yasmine Hammamet organise some beach parties with cool settings and live DJ, but I don't know how often they organise such parties. You can also take a ride on the pirates boat. I think it costs about $18, there is a live DJ on board, a lot of dancing and they stop midway for few minutes and let you jump in the water if you feel like it.
Finally I wish that you will have a happy and safe trip.
