1. One may drink between the first and second cups of wine at the Seder.
2. One must lean while eating Matzah. One may not lean while eating Maror.
3. The Gemara explains what is, and what is not, considered leaning.
4. A woman is not required to lean if she is at the Seder with her husband.
5. A son should lean even if he is having the Seder with his father.
A BIT MORE
1. In contrast, one may not drink between the third and fourth cups of wine. One certainly may drink between the second and third cups of wine.
2. One opinion says that one does not need to lean for some of the four cups of wine. However, the Gemara concludes that one should lean for all four cups of wine.
3. One should lean on one's left side, and not on his right, lest this cause him to choke. One may not lay his body totally flat.
4. However, if she is an important woman, she should lean.
5. However, a student should not lean if he is having the Seder with his Rebbi.