branches shouldnt die, they will always have new leaf growth at their tips, but may have the odd dead leaf. if you clip them then there wont be any bud there, but more up top... i remember readin ed rosenthals closet cultivator book years ago, and he recommended to trim all branches except the ones you want to see as colas... eg. trimming all but between 2-6 branches.. it depends on your growing style, height etc etc...