The sword of Gryfiindor.
The ring.
Marvolo Gaunt's Ring
Ron
Yes, the horcrux inside of Harry Potter
Using the venom from it's fangs.. . .The basilisk's venom is one of the substances used to destroy a Horcrux, which is why Ron and Hermione go down into the Chamber of Secrets in Deathly Hallows, so that they can find a fang from the basilisk's skeleton and use to to destroy Hufflepuff's chalice, the Horcrux.
It depends what Horcrux your talking about, they do find them all and destroy them all though.
Tom Riddles Mothers Ring
because it was a horcrux. it would help to destroy voldemort
The Ring
Well if i remember correctly, dumbledore's ring, of course, was a horcrux. When he realized this, he couldn't take it off and the rings power began to destroy him. He manages to confine the curse to his hand when Snape saves his life with the Sword of Griffindor ( because the sword was infused with basilisk vemon , which is one of the few things that can destroy a horcrux).
No, they went in there to get a basilisk tooth to destroy the horcrux they already had.
From the Gaunt's Horcrux Ring.