I have some difficulties with the question
whether $H(X|Y)=H(Y|X)$?
From my knowledge
$I(X;Y)=H(X)-H(X|Y) = H(Y)-H(Y|X)$
so
$H(X|Y)=H(Y|X)$
only when
$H(X)=H(Y)$
The question is whether it's the last step, can I make a further assumption about the distribution of $X$ and $Y$ or $H(X)=H(Y)$ is a last step and no further conclusions.
$$H(X|Y)=H(Y|X)\iff H(X)=H(Y)$$