We derive some element abundances for the central star of the planetary nebula K648 from analysis of Hubble Space Telescope Faint Object Spectrograph spectra (1200-3300 Å). Carbon is found to be approximately 4 times overabundant with respect to solar values, while oxygen is underabundant and silicon about solar, and He/H=0.6. The stellar continuum indicates a reddening of E(B-V)=0.08 and is well approximated by a synthetic model with Teff=37,000 K and logg=4.0, as found previously by Heber, Dreizler, & Werner. The scaling of the synthetic model with the measured UV flux indicates R=1.3 Rsolar, and thus log(L/Lsolar)=3.45, M=0.62 Msolar, assuming a distance of D=10.3 kpc. The C IV exhibits a wind profile, from which a terminal wind velocity of V∞=1600+/-150 km s-1 is derived and a column density of Ni(C IV)=6+/-3×1015 cm-2. From ground-based spectra obtained at the William Hershel 4.2 m telescope we derive the first measurement of the expansion velocity for the nebula: Vexp([N II])=11.9 km s-1 and Vexp(Hα)=16.7 km s-1. Combined with the nebular radius measured from HST imaging in our previous paper, the velocity yields an expansion age of the object Agekinematic>=4270 yr. This value is slightly higher than predictions from post-AGB evolutionary models for a ~0.6 Msolar He-burning remnant. The photospheric overabundance of He and C, as well as the low luminosity of the central star, are consistent with a post-AGB object that experienced a late thermal pulse and consequent third dredge-up, and which is now in a luminosity-dip He-burning phase. The progenitor mass is fairly low. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555, and on observations made with the William Hershel Telescope (WHT), operated on the island of La Palma by the Royal Greenwich Observatory in the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrofísica de Canarias.