Yes, in fact 2010 has way more characters than 2009.
Yes, Jeff Hardy is going to Smack Down vs Raw 2010
yes
he is in SmackDown vs Raw 2009,Smackdown vs Raw 2010 and the smackdown games some of them
Depends if you cheat
Yes
He's in the game.
Jeff Hardy is not on SmackDown vs Raw 2011
Jeff is not on RAW anymore. He is on Smackdown
Jeff Hardy is not in SVR 2011.
yes
No.
You can't put or unlock Jeff Hardy's entrance music on WWE Smackdown VS RAW 2007.