[Q]Upgrading from KK(emui 3.0) to LP(b630)

hey, I'm about to upgrade my p7 to LP(b630) from the B615 (KitKat) but first I want to know certain things:

1.How I can root on 5.1.1?

2.I can install viper4android without problems

3. Any bugs related?

4. What about battery drains or that type of problems?

Have a nice day :)