have power at outlets and lights, with only hot connected from panel..,, whats going on?
The circuit is finding a path back to source. At some point along the circuit there is a connection to another neutral, or someone connected the ground and neutral and the current is returning through the metal pipes. 

The only way to find whats causing it is to start opening each outlet, light, and junction box until you find the shared neutral, or neutral to ground connection. You should correct this because an improperly shared neutral can cause that neutral wire to over heat.