The captain was cross-feeding both engines from the right tank while the first officer (F/O) was flying, without informing the F/O. The captain then left the cockpit while cross-feeding. Both tank valves and the right boost pump were on. The right tank ran dry, the right engine failed, and the prop autofeathered while the captain was absent. The captain returned, turned on the left boost pump, but left the right boost pump and the valves open, and attempted to restart the right engine. The left engine then failed but this was not recognized by the crew. The electrical system failed due to the attempted restarts and the fact that non-essential equipment was not turned off. The captain did not apply sufficient pull to the emergency gear handle to lower the gear manually. The aircraft was landed on a short wet sod runway, with the gear and flaps up, at a high rate of speed. The aircraft ran off the end of the runway, through a ditch, across a road, and into trees.