Phenol on heating with zinc dust forms

The compound which reacts with excess bromine to produce $2,4,6$-tribromophenol is

The major product of the following reaction sequence is:
Aniline $\xrightarrow[(i) NaNO_2, HCl, 273-278K]{(ii) H_2O, warm} \text{Product}$ $\xrightarrow[(iv) NaOH]{(iii) Br_2, (excess)} \text{Product}$ $\xrightarrow{(v) CH_3I} \text{Final Product}$

The major product of the following reaction is:

Which of the following phenols has the largest $pK_a$ value (i.e.,is least acidic)?

The electrophile involved in the Reimer-Tiemann reaction is