Why is death by perdators more natural or right then death by starvation

Because it is common in the ecosystem to be a predator to someone and a prey to someone else. It is very difficult for animals to die of starvation because the food chain is designed so that the food sources never expire. Bears eat salmon, but salmons keep reproducing and then they feed on on something else, so a bear can't die of starvation because there will always be salmon.

Amphibians live in both land and water is correct.
Amphibians have 3 chambered hearts is also correct.