Money - 1usd = app 2000 pesos (February 2014). It pays off to exchange money at the airport as the rates are much better than in the small exchange offices in the touristic city centers. There are atms in bigger cities. It is recommended not to use the once directly on the streets but inside banks with guards and cameras as cases of coping credit cards in South America are quite common.
Taxi from airport - 10000. There is a taxi office where you can pay and get a ticket for certain route so the prices are fixed and its completely safe.
Accommodation - we stayed in Hotel Familiar (Carrera 10 # 29-66). 25000 per person for 3 people room with 2 beds (one double) and shared showers. Its a peaceful place to stay on a quiet street next to Media Luna. We didnt book anything in advance. We had a hostel recommended by our friend (Casa Viena) but we didnt wanna pay for the reservation and when we arrived they didnt have rooms available but they send us to Hotel Familiar and basically theres nothing to be worried about - whole Getsemani area with main party street Media Luna and neighbouring streets is full with hostels. Best party hostels there are Media Luna Hostel and Mamallena Hostel but they are more expensive and usually you need to book in advance so we decided that it will be better to stay in a cheaper and more quiet place just 5 min from all the pubs - anyway we were going there just to sleep and the rest of the time we were spending out.
We arrived after midnight to Cartagena airport and before we got to the center and found a place to stay it was already around 2 but it was Saturday so Media Luna was still life with people drinking on the street so even though we were crazily tired after all the flights and waiting at the airports we decided to go out and enjoy our first Colombian beers.
Next day we spent just walking around charming streets of Cartagena old town surrounded by defensive walls admiring colourful colonial buildings and balconies with flowers and in the afternoon we went to the city beach Boca Grande which is around 15-20 min walking from the city center and is a little bit chaotic and not so beautiful but still relaxing after few hours of sightseeing.