On any truck that has lift cut out, forks must clear the ground when you're tilted back all the way. If they don't clear when the battery dies, you will drag the heal of the forks when driving back to the battery room. Some drivers want the forks level and off the ground to access the skid better. Higher is better unless....you're on a ramp and the tips wont touch the ground. Forks should at least clear the ground on tilt back, all the way down

Depends on the application. I adjust forks on the 7400 as follows: extend the carriage fully, tilt the forks down. The fork tips should barely touch the floor. Some applications you can raise them even further off the floor. This is assuming you have a single reach, and 42" forks.