SchlongConery and GPIDEAL have given you most of the information that you need. Try to organize as much as you can from here, you don't want to be running around your first day looking for accommodation, you are more likely to "settle" for something just to have a place.
The Canadian dollar is quite low right now, it costs about $132 to buy 100 CUC, not too long ago it was at par. As suggested above, check your change carefully, even at the cash changing cadeca at the airport, they have tried to rip me off almost every time I visit once by about 40 CUC and are not embarrassed when you catch them. I have been going down for a few years now and still have very few friends I know I can trust. Any one you will meet will be trying to make as much as they can off you, either through commissions at restaurants, taxis, casas, girls or other little "scams".
Due to the influx of tourists wanting to see Cuba before the Americans arrive, it has been busier than usual this year. In turn some accommodation prices are increasing, some restaurants too. Average Cuban wages is about 16 to 20 CUC a month for 40 hour work weeks which means that they get paid about 10 cents an hour in government jobs.
The girls you meet in clubs usually have "drivers" outside who are either their boyfriends or pimps, technically one and the same. I had girls promise me they were single, trying to pretend to be my girlfriend for a bigger payday, only for me to bump into them with their boyfriend/husband. One I knew for years, played cool and never asked for anything from me until January this year. The item was too expensive so I declined and she never responded after I came home. I happened to look up her Facebook this week, she is already engaged and living in Italy! The poor guy, she was probably with me while he was funding her visa and flight etc. thinking she is in love with him.
In the larger private clubs the girls pay as much as a 500 CUC monthly fee to work there, so they usually ask you for 100 CUC and don't stay overnight with you. Then ask for taxi fee and gifts... Just walking down the street you will have dozens of girls approaching you, they might ask for less, but watch your valuables on your person and in your room if you take them home.
Once in a while you get lucky and find a girl who is not a pro, but they all need money either for themselves or family. Just inviting her to "hang out" at your hotel or casa doesn't solve her financial problems. If they are seen even just speaking to tourists, they can be picked up by the police. If they have a prior history of being with tourists, they can end up in jail for a few years. Be careful, not only for your sake, but for the girl's too.
