Four Corners is too far to paddle to the dam If you also plan to fish.
This link to a JPP map is good:
http://www.lrn.usace.army.mil/op/jpp..._Use_Guide.pdf
One of the safest ramps is in Hamilton Creek at the sail boat marina. There is another past the marina that most use.
I am cautious of using any ramp on the East side of lake due to security issues. Most ramps now have a fee of $5 to park. They are the safest. Cook's on the East side is easily accessible for a kayak without using their ramp. Water on the channel is 2 feet max near shore then drops 80 to 100 ft. There is a cove behind the channel at Cook's and it is sandy. There is a large flat from Cook's point extending almost to Seven Points.