Acetylation reaction with acetyl chloride is carried out in the presence of which solvent?

Product $(B)$ is

When primary alcohol is oxidized with chlorine,it produces

$A \xrightarrow{KOBr} CHBr_3$
Here $A$ is:

$3 \ mol$ of ethanol reacts with $1 \ mol$ of phosphorus tribromide to give $3 \ mol$ of bromoethane and $1 \ mol$ of $X$. What is $X$?

$CH_3 CH_2 OH \underset{\text{step-}1}{\stackrel{Cl_2}{\longrightarrow}} CH_3 CHO$ $\underset{\text{step-}2}{\stackrel{3 Cl_2}{\longrightarrow}} Cl_3 CCHO$
In the above reactions,the role of $Cl_2$ in step-$1$ and step-$2$ respectively is: