Benzene diazonium chloride on reaction with ethanol forms

The most acidic proton and the strongest nucleophilic nitrogen in the following compound are respectively:

Identify $X$ and $Y$ in the following reactions:

Succinic acid $\xrightarrow{\Delta } (A)$ $\xrightarrow[\Delta ]{NH_3} (B)$ $\xrightarrow[KOH]{Br_2} (C);$ Product $(C)$ will be

The major product in the following reaction sequence is:

Which of the following is the strongest base?