Besides the series of Kingdom Hearts, no.
no
There was a Sora in Final Fantasy II but not the same Sora from Kingdom Hearts.
Assuming you mean "WHO is Sora" Sora is the main character in the Kingdom Hearts video game series. In some of the games, you play as Roxas/Ventus, who is Sora's Nobody, or other half.
Sora hasn't kissed Kairi in any games yet, and he is not in love with Namine there for has never and will never kiss her.
No. When Sora was turned into a Heartless, Roxas was created as Sora's Nobody. Roxas is the shell Sora left behind when he was transformed into a Heartless, even though Sora later got his heart back. So Sora is not Roxas's Heartless; Sora, to Roxas, is what's known as an Other. An Other is a Nobody's original self. None of the Organization XIII members have an Other who's still alive; Roxas and Sora are a unique case.
Roxas is Sora's Nobody, so Roxas was referring to Sora as Roxas' "other" part or half of Roxas.
Yes, Sora does. His brother is Daichi.
none
Possibly Sora Sterling Their other last names are unknown
You can't ever actually FIND and ACQUIRE Shadow Sora. Shadow Sora randomly appears whenever you rely on your (drive) limits too much in the games.
sora. nomura didn't give any of his characters last names
Yes, he was a real character. Whenever someone is turned into a heartless, a new person is created. This is the Heartless' Nobody. Sora turned into a Heartless for a brief period in Kingdom Hearts 1. This is when Roxas was created. Roxas, in basic terms, is the other half of Sora.