If I may, as a person who considers themselves Christian, I would like to address your points from the perspective of my own religious understanding.
To say there is no replacement of the old testament rules to ignore vast portions, perhaps even the majority, of the new testament writings. Jesus changed marriage requirements, the punishment for adultery, reinterpreted the sabbath rules and the rules for cleanliness. After his resurrection he appears to Peter and rescinds the rules on clean and unclean, not to mention that huge recurring bit from Paul et al. about circumcision not being necessary, etc. Old testament law is a covenant between God and the Jewish people, a covenant which Christ ultimately fulfils.
Christianity is in every case a peaceful religion. Jesus never injured anyone, and whatever self-serving arguments some might come up with to justify behavior, the core of Christianity is to put your faith in Christ and become like him in every way. His life stands as an irrefutable counter-argument to any violent perversion of biblical teachings that you or I might come up with, because there is no way to do violence without violating his example.
Part of being a peaceful religion is that Christianity does not seek to overthrow governments or institutions. It instead seeks to change people by witnessing in example to them.
You do not go to hell for not believing. You go to hell for committing evil. Unholy things cannot be united with a holy God. If that sounds unpalatable, apparently Christ agreed, since he was willing to suffer and die to circumvent that on your behalf. Do all non-believers (upon death) go to hell without any secondary consideration? Some people do think that, but that's not laid out in any clear fashion. What is clear is that if you repent of evil deeds and choose Christ's path instead, you may have ever confidence of remaining in that forever.