A shunt is connected in parallel with a galvanometer. Why?

In the following circuit, assuming point A to be at zero potential, then what is the potential at point B?

In the circuit shown, if the 10 $$\Omega$$ resistor is replaced by a resistor of 15 $$\Omega$$, then what is the amount of current drawn from the battery?

A moving coil galvanometer has a resistance of 60 $$\Omega$$ and it indicates full deflection on passing a current of 4.5 mA. A voltmeter is made using this galvanometer and a 4.5 k$$\Omega$$ resistance. The maximum voltage, that can be measured using this voltmeter, will be close to