Which of the following will $NOT$ undergo $S_{N}1$ reaction with $\text{OH}^-$?

What will be the major product of the following reaction?
$(CH_3)_2CH-CH_2Br \xrightarrow{CH_3O^- / CH_3OH}$

The compound $A$ (major product) is

Given below are two statements:
Statement-$I$: High concentration of strong nucleophilic reagent with secondary alkyl halides which do not have bulky substituents will follow $S_{N}2$ mechanism.
Statement-$II$: $A$ secondary alkyl halide when treated with a large excess of ethanol follows $S_{N}1$ mechanism.
In the light of the above statements,choose the most appropriate from the options given below:

When ethanol is reacted with $PCl_5$,it gives $A$,$POCl_3$,and $HCl$. Compound $A$ reacts with silver nitrite to give the major product $B$ and $AgCl$. What are $A$ and $B$ respectively?

The reaction of $C_6H_5CH=CHCH_3$ with $HBr$ produces