What will be the product of the reaction with $HBr$?

The following reaction sequence is given:
Phenol $\xrightarrow{NaOH} X$ $\xrightarrow[(ii) H^+]{(i) CO_2} Y$ $\xrightarrow{(CH_3CO)_2O/H^+} Z + CH_3COOH$
The correct statements about $Z$ from the following are:
$I$. It is $o$-hydroxybenzoic acid.
$II$. It is a non-narcotic analgesic.
$III$. It acts as antipyretic.
$IV$. It acts as antihistamine.

Reaction of phenol with dil. $HNO_3$ gives

Assertion $(A)$: $pK_a$ of phenol is $4.19$ and that of benzoic acid is $10$.
Reason $(R)$: Phenoxide ion is stabilised by non-equivalent resonance structures,whereas benzoate ion is stabilised by two equivalent resonance structures.
The correct option among the following is:

Explain why $p-$nitrophenol is more acidic than $o-$nitrophenol?

How many $\sigma$ (sigma) and $\pi$ (pi) bonds are present respectively in the final product obtained by the Reimer-Tiemann reaction of phenol?