(N/A) $(i)$ The ammeter reading will decrease (become half). This is because resistance $R$ is directly proportional to length $L$ $(R \propto L)$. When length is doubled, resistance doubles, and according to Ohm's law $(I = V/R)$, the current $I$ becomes half.
$(ii)$ The ammeter reading will increase (become two times). This is because resistance $R$ is inversely proportional to the area of cross-section $A$ $(R \propto 1/A)$. When the area is doubled, resistance becomes half, and consequently, the current $I$ becomes double.
$(b)$ It means that $1\, J$ of work is being done to move a charge of $1\, C$ from point $A$ to point $B$.