ddburge - There is no wrong way to sink cedar. If you built the lake originally you will know where the breaklines are. I would tow some medium size trees out to these breaklines and sink them. Typically I determine where I want to lay the piles, then I place a milk bottle for a marker and start towing. When you are finished simply remove the marker.

Regarding your question of what depth to start your piles. I would suggest 6' and stop at 25'. A row of trees extending between these 2 depths allow the fish to travel shallow during the Spring and Fall and deeper during the Summer and Winter. It is a travel corridor and it concentrates the fish.

You may also want to drop a few along the shoreline to attract the fish during the spawn.

Hopefully this answers your questions, if not let me know.