Can one someone please guide me with the current flow direction and amount of current (Through Gate) (how shall I calculate it) for a P Channel Mosfet? For example if I connect the Gate to something that can sink a very low amount of current, then what happens?
The gate of a MOSFET looks like a capacitor to the driving circuit. It therefore takes current to change the gate voltage, but no current to hold it at a particular voltage.
If you connect the gate of a P channel MOSFET to something that can sink only a small amount of current, the gate voltage will go low slowly. Whether that's a problem or not depends on the rest of your circuit.