for the second part of your question, theres no such thing. we all have different needs that we want out of roms/kernels, and every single one of us uses our devices differently, so you really have to try them out to find your best. no one else knows whats best to you except you.
battery is all about your personal usage, your personal setup, and greatly on the quality of phone/data connection that you have. everything else is of minor importance to battery life.
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