Not really
but Sasuke's getting darker day by day...
i would have to say "Suigetsu" According to sasukes flashbacks in recent shippuden episodes Sasuke thinks that Naruto Uzumaki And Suigetsu are the same personality wise. :D
yes u can change your personality
No
He doesn't have one.
Really good!
Sharingan
Yes, it is alaways possible to change your personality. You just have to figure out, what you want to change about your current personality, and figure out how you are going to do it.
Suaskes (?) If you're talking about Naruto, Sasukes parents actually get killed by Itachi (Sasukes older brother)
If you mean the time when he fought Naruto in 1 tail form at the Vally of the End, it's because of the cursed seal.
Fugaku and Mikoto Uchiha
July 23
July 23rd - Pisces