  For finitely generated modules $M$ and $N $ over a commutative Noetherian
local ring $R$, we give various sufficient criteria for detecting freeness of
$M$ or $N$ via vanishing of some finitely many Ext modules
$\textrm{Ext}^i_R(M,N)$ and finiteness of certain homological dimension of
$\textrm{Hom}_R(M,N)$. Some of our results provide partial progress towards
answering a question of Ghosh-Takahashi and also generalize their main results
in many ways, for instance, by reducing the number of vanishing. Certain
special cases of our results allow us to address the Auslander-Reiten
conjecture for modules whose (self) dual has finite projective dimension. Along
the way, we also provide a negative answer to a question of Gheibi-Takahashi on
characteristic modules. Among other things, the notion of residually faithful
modules and certain generalizations of it play a crucial role in our study. As
some applications of our results, we provide affirmative answers to two
questions raised by Tony Se on $n$-semidualizing modules. Namely, we show that
over a local ring of depth $t$, every $(t-1)$-semidualizing module of finite
G-dimension is free. Moreover, we establish that for normal domains which
satisfy Serre's condition $(S_3)$ and are locally Gorenstein in codimension
two, the class of $1$-semidualizing modules form a subgroup of the divisor
class group. These two groups coincide when, in addition, the ring is locally
regular in codimension two.
