You should start with your chassis level.
It's just another tuning option, you can change it if the car doesn't do what you want.
You're right about if the front end is lower than the rear that than you'll get more steering, and you wil gain more rear traction if the rear end is lower than the front (but this isn't the best way to create rear traction)
I prefer to have the front end A bit lower than the rear, because that fits to my driving style.