You really don't need pesos. We changed 100 euro per person and did not use 50. And we only used because we had. So change a little bit, but don't worry. They accept everywere euros (or dollars).
We stayed in casa particulares, private houses. And that was nice. All times we had a private bathroom, the rooms were clean. Internet was quite bad, but everywere we had. They had, but you always have to ask and then they turn it on. Sometimes it was ok sometimes it was very slow.
Breakfast was great, 5 euro per day (some houses offers breakfast with a choice of 3 euro or 5 euro, but we took the most expensive then). Dinner was at the families too, 10 euro per dinner.
In Vinales we used restaurants. The dinner at families was enough, but don't expect haute cuisine. We had every day rice and green beans and then some advacado fruit and chicken, fish, pig. So not bad, but not luxery. After a week we were very happy that we found a shop that sold a can of pepsi coke. The mango juice and water and tea started to get boring, haha.
No, serious, staying at private houses is way much better than a hotel.
The week of the worldchampionships we stayed in a 5* luxery all inclusive hotel in Varadero, Royalton Hicacos. Oh yes, the rooms were nice, but further it is a very boring hotel. I just came there because it was part of that photocompetition. But it has nothing to do with the country. You don't see any culture from Cuba if you stay in the hotel. The best thing was that they had home made icecream. The food further was more than enough, but most times mediocre quality, all made for big groups. The a-la-carte restaurants were better. They had french fries, but no mayonaise, so take your own if you want it. Haha.
In Havana we stayed in a hostel, that was also very nice. No luxery, only cold showers, but yes, it was great.
Diving in Varadero is 85 dollar for 2 dives, but competitors of the world championships had to pay 92 for extra trainingdives (dives are without guide, so that is really great). We did not do any extra dives in Varadero. But the people who did and paid in advance are still waiting to get their money back from the dives they did not get due to weather conditions. So don't pay in advance.
In the bay of pigs are not big hotels, only some smaller ones. There is a divecenter in Playa Giron, but their dives don't sound nice. 25 per dive including all equipment, but only 45 minutes and then dive 1 is to the left, dive 2 is to the right on the same divespot. That is what I heard, don't have real experience. But we did dives sometimes of 85 minutes on the ali80 tank.
There are maybe for some people safety concerns about diving in Cuba. Our diveguide did not have oxygen. It is not available there. So nitrox is also not available. If divecenters have oxygen for emergency, I don't know. We have done some deco on our tanks with just air, so this is something you have to think about if you go diving in Cuba. I have not seen the compressor, he filled our tanks not at his home. It took hours, but there was no smell in the compressed air. Most times I try to look at the compressor of a divecenter.
About oxygen for emergency, they said they have for the worldchampionships, but we had a fishingboat and I haven't seen any oxygen cylinder in our boat. So maybe it was on the boat with all the spare tanks that could go to all the competiton boats, maybe it was hidden in our boat. They said they had, but nobody said where it was. I don't know and saw no need to ask further. I am sure that if something happened there would have been oxygen, but I don't know if this is there for every dive outside the competition. For the championships there were doctors standby and a decotank, and an ambulance, but my buddy hit her toe and it was bleeding, so asked for a plaster, and they did not have an easy first aid kit in the harbour, so she had to walk to the ambulance that was just there for use in the harbour. That was really funny, 8 people around her to just put a plaster over a toe. So best is to take just some plasters with you if you go to a divesite. Don't expect that others have it.
You cannot buy such things in pharmacies there, they are all empty.
Divecenters are most ssi there.