Ed, as far as being "expected" to lead troops into action, as you asked, I would have to say that colonels commanding regiments were the highest ranking officers expected to lead from the front.

Although in theory brigadier-generals were expected to deploy the regiments of their brigades via staff officers, it can safely be said that, on the Southern side at least, brigadier-generals almost routinely led their brigades in person. In no subsequent war did the casualty rate of general officers approach anywhere near that of the Civil War. Also, though not commonplace, it was not unknown for major-generals commanding divisions to lead their troops, e.g., Pat. Cleburne at Franklin.