  We carry out detailed spectral and timing analyses of the $Chandra$ X-ray
data of HD 179949, a prototypical example of a star with a close-in giant
planet with possible star-planet interaction (SPI) effects. We find a low
coronal abundance $A({\rm Fe})/A({\rm H}){\approx}0.2$ relative to the solar
photospheric baseline of Anders & Grevesse (1989), and significantly lower than
the stellar photosphere as well. We further find low abundances of high First
Ionization Potential (FIP) elements $A({\rm O})/A({\rm Fe}){\lesssim}1$,
$A({\rm Ne})/A({\rm Fe}){\lesssim}0.1$, but with indications of higher
abundances of $A({\rm N})/A({\rm Fe}){\gg}1, A({\rm Al})/A({\rm
Fe}){\lesssim}10$. We estimate a FIP bias for this star in the range
$\approx{-0.3}$ to ${-0.1}$, larger than the ${\lesssim}-$0.5 expected for
stars of this type, but similar to stars hosting close-in hot Jupiters. We
detect significant intensity variability over time scales ranging from 100 s -
10 ks, and also evidence for spectral variability over time scales of 1-10 ks.
We combine the $Chandra$ flux measurements with $Swift$ and XMM-$Newton$
measurements to detect periodicities and determine that the dominant signal is
tied to the stellar polar rotational period, consistent with expectations that
the corona is rotational-pole dominated. We also find evidence for periodicity
at both the planetary orbital frequency and at its beat frequency with the
stellar polar rotational period, suggesting the presence of a magnetic
connection between the planet and the stellar pole. If these periodicities
represent an SPI signal, it is likely driven by a quasi-continuous form of
heating (e.g., magnetic field stretching) rather than sporadic, hot, impulsive
flare-like reconnections.
