yes
No, Snape is the half blood prince. His mother's name was Eileen Prince, who was a witch, and his father, Tobias Snape, was a Muggle. In Harry Potter and the Half Blood Prince, Snape admits this to Harry.
No. But he works for the 'Light Side'.
I believe you mean Snape, as in Severus Snape. Yes, he was good. Harry finds it out after Snape's death in Deathly Hallows.
In my opinion the biggest secret is that Severus Snape is good.
Yes, in the end, it turned out Snape had been working with Dumbledore the entire time.
Good and bad are subjective terms, people do both good and bad. Severus Snape certainly wasn't without fault - he did a lot of bad things, but he also did a lot of good things. Snape joined the death eater initially, but was later instrumental in destroying Lord Voldemort.
He can never be considered a good person but he did fight for the Order of the Phoenix rather than the Death Eaters.
Voldemort and his Death Eaters. He used to hate Severus Snape before discovering he was on the good side. He used to hate the Malfoy's before they changed sides and before Narcissa saved his life.
I think he came out as being good Dead. Bitter. Hopeless. Angry. Sad... etc
Yes, he has been on Albus Dumbledore's side since 1980 when a threat was made on the life of Lily (Evans) Potter.
Well, Lily Potter and Severus Snape were friends since they were about 8 years old. snape loved Lily since the day they mat. Lily didn'y know he loved her, but they were great friends until their fifth year when James Potter casted Levicorpus upon Snape, causing him to hang upside down by his ankles, allowing his trowsers to fall. When Lily stuck up for him, Snape called her a mudblood, and she never forgave him. During the time they were good friends, Snape was obsessed with the Dark Arts, and Rowling claims that is Snape didn't love the Dark Arts as much as he did, Lily might have loved him
Severus Snape was the main Death Eater that turned good...he was the bravest of them all. After his love, Lily, died, he sided with Dumbledore to keep Lily's son safe. The other Death Eater that turned good was Regulus Black.