Who gets to decide who is "evil"? Evil from one person's point of view might be greatness from another's. When we start claiming we can decide who is "evil" enough to deserve death, we are starting down a slippery slope.
"Evil" is a subjective and relative term. Pictured in this was Adolf Hitler. Some would say he is "evil", especially for subjugating his own country to fascism and for killing millions in horrible ways. However, Stalin, the dictator of the Soviet Union at the same time Hitler was the Fuhrer of Germany, was very similar, but managed to kill up to 40 million in his reign. Because he helped the US defeat Germany in WW2, however, he is generally regarded as the lesser evil. People today openly proclaim being Communists and even Stalinists, but almost none are National Socialists or Hitler-followers. Once we say "the evil have no right to live", we only have a few short steps until we're at "the Jews have no right to live."
The right to live is unconditional.
No one is so important that they can usurp the rights of another. No one can make the choice whether another has the right to live, to do so would be speading the evil which you wish to destroy.
Yes, unless they infringe on or violate the rights of others to live.
hell no. They need to go to hell with their buddies as well.
Only exception is if they are Bane.
No. An evil person that breaks humans laws so that it intentionally leads to the death of other humans should not be allowed to live. Human intelligence requires us to punish individuals that break laws and rules that are devastating to others and to society. When someone like Hitler kills others mercilessly, logic requires us to exact punitive measures - including the death sentence!