The On-resistance information tells you what gate-source voltage the manufacture uses to characterize the on-resistance. That means you should not normally use less than that if you want the MOSFET to operate as a switch with a low on-resistance.
Both the transistors you listed are characterized at both a Vgs of 4.5V and 10V so you can use either value, depending upon how low you want the on-resistance to be. Thus 6V for your circuit should be fine unless you want the absolute lowest on-resistance.
If you operate the N-MOSFET from a TTL output, which is typically only about 3V, you should add a pull-up resistor (say 1k) from the TTL output to the +5V voltage so that the gate voltage goes to 5V when the transistor is on.
Thanks very much.
Can you tell me why there is a choice between of switch on voltage of 4.5v-10V? is one or other better? I have changed the resistors to give (negative 9Volts).
Am I correct that, now with the higher pull up voltage for the 'P' mosfet is it best to switch the 'P' Mosfet with PWM, leaving the 'N' mosfet to switch on/off and be used for braking?
Here is the latest schematic version, would you check this please?
As before I am using 'N' IRF7413ZPBF and P IRF7424PBF mosfets, but will this circuit work for all Mosfets?
EDIT: Pots added for testing.