  We compute the leading order (in $\alpha_s$) perturbative QCD and power
($1/m_b^2)$ corrections to the hadronic invariant mass and hadron energy
spectra in the decay $B \to X_s \ell^+ \ell^-$ in standard model. This is done
both by using the heavy quark expansion technique (HQET) and a perturbative-QCD
improved Fermi motion (FM) model which takes into account $B$-meson
wave-function effects. The corrections in the hadron energy ($E_H$) spectrum
are found to be small over a good part of this spectrum in both the methods.
However, the expansion in $1/m_b$ in HQET fails near the lower kinematic
end-point and at the $c\bar{c}$ threshold. The hadronic invariant mass ($S_H$)
spectrum is calculable only over a limited range $S_H > \bar{\Lambda}m_B$ in
the heavy quark expansion, where $\bar{\Lambda} \simeq m_B-m_b$. We also
present results for the first two hadronic moments $< S_H^n>$ and $< E_H^n>$,
$n=1,2$, working out their sensitivity on the HQET and FM model parameters. For
equivalent values of these parameters, the moments in these methods are
remarkably close to each other. Using the FM model, we study the effect of the
experimental cuts, used recently by the CLEO collaboration in searching for the
decay $B \to X_s \ell^+ \ell^-$, on the hadron spectra and hadronic invariant
mass moments. The constraints following from assumed values of $< S_H^n>$ on
the HQET parameters $\lambda_1$ and $\bar{\Lambda}$ are worked out. Data from
the forthcoming B facilities could be used to measure the short-distance
contribution in $B \to X_s \ell^+ \ell^-$ and determine the HQET parameters
$\lambda_1$ and $\bar{\Lambda}$. This could be combined with complementary
constrains in $B \to X \ell \nu_\ell$ to determine them precisely.
