The electrostatic coassembly of a block copolymer polyelectrolyte poly(ethylene oxide-block-poly(methacrylic acid), PEO705-PMAA(476), and oppositely charged surfactant, N-dodecylpyridinium chloride (DPCl), has been investigated by a combination of isothermal titration calorimetry (ITC), spin-echo NMR spectroscopy, and time-resolved SAXS measurements. The study (i) confirms the conclusions drawn from our earlier study [Macromolecules 2012, 45, 6474] by scattering and microscopy techniques (i.e., the ITC curves can be interpreted using arguments consistent with conclusions of the earlier study) and (ii) yields new insight into the thermodynamic and kinetic behavior of the self-assembling system. The most important finding obtained by stopped-flow time-resolved SAXS measurements concerns the surprisingly high rate of processes of creation of structurally ordered cores of self-assembled surfactant-polyelectrolyte nanoparticles (<50 ms).