Apologies. I've been on the move so much that I've taken too long to post again in this thread. In the meantime, there have been some excellent reports and recommendations, so I won't need to cover the same territory but will add a few comments.
First, I would endorse Millboo's post above. An all-inclusive resort is not likely to expose you to much of the local culture, unless you work really hard at it. Much more interesting to mix it with the locals, in some way with which you are comfortable, whether that is through hotels, which would be State-owned, in the main, or private hotels, or a casa particular (homestay accommodation).
We stayed at a mix of those accommodation categories, as we moved around the country. The standards are immensely variable but then that's the case everywhere, really. In Havana, in particular, it may be advisable to inspect your hotel room before accepting it. We found the first room we were allocated - in what was supposed to be a 4 star hotel - had not only no window at all but only a very small panel in the door that could be opened for a tiny shaft of light (no air, as I recall), coming from a public walkway outside the room. The lack of window aside, the room itself would have been fine, in terms of size and layout - but it was oppressively hot and did not have aircon. Needless to say, we didn't accept it.
The replacement room, for which we paid a supplement - but negotiated way down from the asking price - was in fact a suite, so about three times the size of the first, and with two balconies, one from the bedroom and one from the (rather austere) sitting room. (The one thing it had in common with the rejected room was that it, too, was dreadfully hot. It did have an aircon control panel and visible ducting. And it
was possible to turn it to the On position. But that was the end of the story.)
In another location, we had a reserved room in a "resort" hotel but ran into an impasse, where we were being told that we must move to accommodation in the community. Eventually, we extracted the reason, which was that the hotel could not guarantee that there would be hot water in the one remaining room available for us. Rather amusing, as I don't recall finding hot, as opposed to tepid, water in any of our accommodation over the nine nights.

Even more amusing, as some of the bathrooms encountered had signs advising the need for caution as the water temperature was "50C". One - more accurately - stated "+/-50C".

We were happy to take the room, regardless, and found the water to be as hot (or not) as anywhere else we stayed.
Our experience in a casa particular was fine. Our room was in one house, fairly spartan but clean and with local character, and we took meals in the main family house across the street. The patriarch had been a restaurateur and the family house had been upgraded with a large rooftop terrace that served as a breakfast room for guests and, in our case, as a private dining room under the stars on our arrival evening. A lovely treat.
Most of our transport was via taxi-cabs, some of which are permanently on touring commissions. In some of them, the aircon worked. (Did I mention it was hot? Low to mid-40s, and extreme humidity at the time we were there. Not a reason not to go to Cuba in August but it would certainly be more comfortable in other months.)
We used local guides in each location and, again, the quality varied immensely. A great guide for several days in Havana and nearby, and a lovely young woman in Trinidad. A couple of others were missable. Some of the drivers had useful levels of English, too, which added to the sources of information available to us and enriched the experience further.
Others have commented on the food. On our travels, there was no problem at all with quantity; in fact, the opposite was the case. In some places where there was a type of set meal, we were served four or five times as much food as we could possibly eat. I just hope that the excess was used by the family or staff!

In one or two places, we had very good meals. Most were of acceptable quality, but nothing more than that.
A few comments on some of the practical logistics that have been queried.
Tourist cards: We booked guides and accommodation etc through an agent who has helped us with logistics in other parts of the world that were new to us. (I usually act as my own TA for all bookings but have used this person in places such as Oman, and he generously agreed to assist with the basics in Cuba, although I booked all our flights etc.) It was cheap and straightforward. They can also be obtained on the spot.
Telephone and Internet: We were told before we travelled that the main hotels would all have Internet and that our Oz mobiles would work.
Not so.
One of our four star hotels had a "Cyber Café".
To be accurate, it had a door marked "Cyber Café".
There was no Internet at all in the hotel "that week". Who knows if there was a service the week before or the week after? Perhaps, perhaps, perhaps.
The Parque Central Hotel, which was about a 20 minute walk from two of the places we stayed in Havana, was the only place we found that had Internet available on demand. There were others that advertised the service but could not deliver.
Our mobiles had no service at all, anywhere in the country, despite promises to the contrary. We were told that we could get local access - but that, at the time we were there, the wait for the service to be connected would be a week! We checked the queues each day and they were horrendous on all days except one, when the queue at the Telco service place nearest to us was only about a quarter the usual length. The excitement was short lived, though, when I discovered that people were queuing to read the notice in the window that said the office was closed for fumigation! By that time, we just found it funny.

It may be relevant that we were both using iPhone 6. Some older models (allegedly) worked - but we did not actually verify that claim.
Credit Cards and Currency Exchange: Again, we were told that our first hotel would accept Credit Cards.
It did not - "this week". I can't guarantee one way or the other for other weeks.
The hotel, according to the local tour agency's notes, would also change money (specific currencies, such as Euros and Sterling) at the same rate as the Bank.
It did not.
In fact, we could not change even the smallest amount there. I think that was also a "not this week" response, but I may be gilding the lily.
The Bank, a few blocks from the hotel, was open for extended hours, with the usual queues but no hassles with changing major currencies.
I've rambled on longer than I intended, so will stop. If there are any specific questions, I am happy to respond.
This post has focussed on the prosaic elements and doesn't touch on the colour and motion of the trip. It was endlessly fascinating and well worth doing.
As everyone says, the country will change enormously in the near future. After our time there, I agree completely with the statement but the challenges are so immense that it is almost impossible to predict just how those changes will impact on the culture, the economics, the political structure and the social systems. Whichever way it goes, it will be worth watching.
