The snake is called "Nagini". It also appears in earlier stories, starting with Harry Potter 4.
Nagini
nevile longbottom
yes. in bathilda bagshot's home.
She is the author of "A History Of Magic", although in Deathly Hallows she was killed by Voldemort and when Harry and Hermione met her, she was actually Nagini (Voldermort's snake) in disguise.
nagini [voldemorts pet snake]
Neville Longbottom beheaded Nagini, the snake.
Neville Longbottom repays Harry Potter by killing Lord Voldemort's snake, Nagini, the last horcrux to be destroyed in Harry Potter and the Deathly Hallows.
The main antagonist in Harry Potter and the Deathly Hallows is Lord Voldemort, a dark wizard seeking to conquer the wizarding world and kill Harry Potter. Nagini, Voldemort's snake, also plays a key role as an antagonist in the story.
I believe you mean Snape, as in Severus Snape. Yes, he was good. Harry finds it out after Snape's death in Deathly Hallows.
The last remaining horcrux was the snake, Nagini. Neville destroyed it with the Sword of Gryffindor.
Harry does not get all of the horocruxes at once. He receives the first one in the second book when he finds tom riddles diary. He finds another one during the 6th book when Dumbledore has the ring on his finger. The locket is also found at the end of the 6th book. The rest are found spread out throughout the 7th book. Harry is the last and 8th horocrux.
Voldemort's snake, Nagini, was not disguised as Bathilda Bagshot, but instead was residing in Bathilda's corpse for a short while.