Why high current MOSFET is driven with another transistor
More often than not with P-Channel devices tied to logic like that the transistor is used because the voltage on the drain of the MOSFET is greater than the logic supply level. If the supply is even higher there will be a resistor between collector and gate too to form a voltage divider to set the gate voltage.

In this case though, assuming Vcc IS the logic supply level I'd say it's just a plain old inverter. Also as Wesley mentioned, it guarantees the gate goes to Vcc when off.

It could also be because the gate capacitance of that mosfet is large enough to need the extra pull to drag it down.

I have no idea what image 2 has to do with the rest of the question.