Custom Rom and Root

Hi folks i need answer for my questions please .
My device : GT-S6312 4.1.2.3 JB

Can i install android 4.3 or 4.2 ? if yes how ?
What is the stock kernel ? Do i need to install it ?
like this ( Stock Kernel (I tested it on Stock Kernel only). Flash it over Custom Kernel, at your own risk.) FROM [ROM] [GT-S6312] [JB 4.1.2] Bulldroid v2 (26-05-2014)
Framaroot support my device ?

Thank you ...