I want to be a tiger in my next life.
That would certainly be an exciting recarnation, as you would be an apex predator. You would also be able to prey on deer and bovids, as tigers are known to do that.
Yes, that is there main source of food. They don't eat any plants.
You are indeed correct, it is sad to think about how tigers have lost 93% of their historic range over the last 100 years though, humanity can be quite cruel in that regard.