  Motivated by a recent experiment of Song \emph{et al.} [Science {\bf 332},
1410 (2011)], we theoretically study the spin dynamics, charge dynamics, and
point-contact Andreev-reflection spectroscopy (PCARS) of two-band iron-based
superconductors of a possible extended $s_\pm$-wave pairing symmetry. We
consider the case of a dominant $s_\pm$ gap blended by a secondary extended $s$
component in which gap nodes can develop in the Fermi pockets near zone corner
and/or boundary. Due to the strong nesting effect associated with nodal
regions, dynamical spin and charge susceptibilities can exhibit strong peaks at
momenta near $(\pm\pi/2,0)$, $(\pm\pi,\pm\pi/2)$, as well as $(\pm\pi,0)$ in
the unfolded Brillouin zone. For PCARS, considering an anisotropic band effect
induced by an applied voltage, [100] differential conductance can exhibit a
$V$-shape behavior manifesting a gap node occurring in such direction. It is
highly suggested that the above features can be experimentally investigated to
help sorting out the pairing symmetry of iron-based superconductors.
