What do you mean by how it is split? Do you mean how do you get paid as an O/O?
If that is what you mean, you get 62% of the gross, or what the load pays. Some agents pay up to 65% on some low paying loads. Gross is determined by how many miles it is between the pickup and delivery.
As to whether to sign up as an agent, I believe you'd have to talk to Ike Tate at corporate. They discourage agents from having their own trucks, but I'm sure there are ways around it as several agents do have trucks.
Hope this helped!