Reincarnation is not an exclusively Hindu or Buddhist concept, but it is part of the history of human origin. It is proof of the mindstream's capacity to retain knowledge of physical and mental activities. It is related to the theory of interdependent origination and to the law of cause and effect.
Criminals, people who commit crimes, usually society rejects these people. They are also part of our society. Give them some form of punishment to say they were wrong, but show them they are part of society and can change. Show them compassion.
If you help others with sincere motivation and sincere concern, that will bring you more fortune, more friends, more smiles, and more success. If you forget about others' rights and neglect others' welfare, ultimately you will be very lonely.