In line of battle formation, all ships will follow the exact course taken by the lead ship, so tacking while keeping line formation is not a problem. I haven't gotten into a situation where I had to reverse the line as a fleet yet. Its not a formation option, but perhaps you can do it by ungrouping and then regrouping your fleet in in such a way as to have the last ship become the lead ship; not really sure about that right now though.

IsItStillThere, what kind of problems are you having with grouping/formation?