Paint Wreckage is self explanatory. Sometimes you want an easier way to click and reclaim wreckage. Note, this would not include reclaim of living units. It would only reclaim wreckage. Such a right click paint brush would be very useful.

Paint Guard is less obvious, but just as useful. Sometimes you want your units to guard a group of units. Maybe, you want to send some engineers along with your battle group to repair the wounded. Maybe you want your bodabooms to stick with the tanks but not take the lead. Bodabooms are so fast. Maybe you want your air group to support your land group. In any case a paint guard would be helpful in these situations. It would be nice if units could be assigned to guard entire groups through the strategic zoom auto groups as well.