"Do you know if at-risk and basis for each passive investment are required for a RE professional who has elected to group passive activities? "

After more reading on this topic, I think the answer is that basis and at-risk calculation ARE required.  Because activities can be grouped and regrouping are allowed, there is a possibility that an activity will be separate. Once separated losses will then be subject to basis and at-risk limits. Therefore, with that possibility, basis and at-risk calculation would be a good idea.