Hey, PP! If you want to know about Santeria, ask a Cuban!
"Santeria" is a syncretization of Catholicism and the religion of the Yoruba, who were brought to Cuba in large numbers from Nigeria as slaves. Once in Cuba, they were compelled by slaveowners to adopt (at least the trappings of ) Catholicism. Soon the Yoruba began associating certain Saints with the gods of the Yoruba pantheon. So in this way they continued their indigenous religious practices in Catholic disguise. (Candles and food offerings/sacrifices placed in front of the image of a certain Saint.)
Santeria is a well known and fairly widespread (in varying degrees) practice in Cuba and in areas where large numbers of expatriate Cubans gather. Certainly it was all around in Miami, where I grew up. Most Cubans are not full-fledged Santeros, but most of our families DO have a strong connection/ devotion to a patron Saint that has a prominent role in Santeria. Many of us watched grandparents offer a particular Saint their favorite fruit, a specific color candle, say special prayers on a particular day of the week.
This is because, in Santeria, every person is seen as belonging to a particular Saint who guides them throughout their life.
Most of us just assumed it was Catholic until we got older and figured out that maybe there was something more going on...
Full-on Santeros and Santeras DO perform animal sacrifices (non-santeros do NOT.) In Miami there is an actual "Santeria Church" where they have a county permit to perform these sacrifices. Their ceremonies are much more African than Catholic.
The percentage of Cubans who actually do these sacrifices is small. Most folks stick to candles and fruit. Though it is not uncommon for a Cuban who is facing a BIG crisis to consult a Santero to take care of the problem. Most of us know at least one family member or friend who is a Santero. Also, nearly every Cuban neighborhood has a Botanica (herbalist/Santeria supply store/religious goods) where a Santero can be easily found.
A lot of the scarier things that are associated with Santeria in the public mind (black magic, etc.) are actually related to another African religion from the Congo tribe, Palo Mayombe. I really don't know about it and I will not talk about it.
In Miami Santeria is fairly visible and prominent, medical antropologists have studied folk healers and herbalists who are Santeros, and now it is accepted practice at many Miami hospitals to allow Santeros to conduct healing/cleansing rituals to aid the recuperation of their Cuban clients who request this.
Prominent Saints who also have a role in Santeria include: Our Lady of Charity (la Caridad del Cobre) the patroness of Cuba, Our Lady of Regla, Our Lady of Mercy, St. Peter, St. Barbara, St.Lazarus, St. Anthony, etc. (it is a long list)
You will find that almost all Cuban families will have a statue of one of these Saints, even if they do not practice Santeria in any form. It's just that these Saints are so important and prominent in Cuba, that folks learned to love and revere them as children and taught their own kids to also revere them.
And yes, I do have family members who, at one time or another were involved (in varying degrees) in Santeria and I was raised with it (although I do not practice it now).