Re: Can Data only receive order from Riker (& up) ?
TNG itself is a little unclear on this point, as Troi had to take a test to become qualified as a bridge officer, but during "Disaster" is deferred to by the far more qualified (in military terms) Ro and O'Brien ... so it's a little unclear what she gains when she passes the test in "Thine Own Self," besides the rank of commander..
AFAIK, the test wasn't simply to qualify for bridge duty - Troi already had that. It was so she could *command* a bridge watch.
In labor news: Longshoremen walked off the piers today. Rescue operations are continuing.