The leopard and Nicaraguan's care are going to be pretty similar. The Leopard is a morph of the Sonoran Desert boa. Both stay fairly small and all but the biggest should be easily caged in 3'x 2'X 1' enclosures. I keep my BCI at 88-90 degrees on the warm side and 82-84 degrees on the cool side. Humidity should be fairly high around 60-70%.
Peruvians are much bigger than the aforementioned boas. I have seen Peruvians around 11 ft before. You will at the very least need a 4' x 2' x 1' enclosure for males and small females. These guys area little trickier to keep to my understanding and need a little extra heat. Not much though. Maybe 90-92 degrees on the warm side and around 85 on the cool side. I am not sure on the humidity of these guys.
I would recommend a Nicaraguan for your first boa as they are less pricey than the other two and much more forgiving when it comes to temp and humidity changes. As for breeding tips I would suggest to go to Jeff Ronne's site www.theboaphile.com and look for the article he wrote on breeding. There is too much information on it to post here.
Hope I could help, Chris