This is the best book on the lares: Dancing lares. Basically they seem to have been spirits of place. As well as those in the home (lares familiares), there were the local ones (lares compitiales) worshiped in little street shrines in town and also in the countryside, the marine ones (lares permarini) who had a temple near Rome, the lares praestities with a temple in the heart of the city. The lares compitiales has a street festival, the compitialia, usually on January 1, where neighbours ate roast pork and drank a lot.
The myths tend to be taken over from Greece without any real alteration.