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(Abridged) We use optical spectroscopy to investigate the disk, wind, andaccretion during the 2008 ZCMa NW outburst. Over 1000 optical emission linesreveal accretion, a variable, multi-component wind, and double-peaked lines ofdisk origin. The variable, non-axisymmetric, accretion-powered wind has slow($\sim $0 km s$^{-1}$), intermediate ($\sim -$100 km s$^{-1}$) and fast ($\geq-$400 km s$^{-1}$) components. The fast components are of stellar origin anddisappear in quiescence, while the slow component is less variable and could berelated to a disk wind. The changes in the optical depth of the lines betweenoutburst and quiescence are consistent with increased accretion beingresponsible for the observed outburst. We derive an accretion rate of 10$^{-4}$M$_\odot$/yr in outburst. The Fe I and weak Fe II lines arise from anirradiated, flared disk at $\sim$0.5-3 $\times$M$_*$/16M$_\odot$ au withasymmetric upper layers, revealing that the energy from the accretion burst isdeposited at scales below 0.5 au. Some line profiles have redshiftedasymmetries, but the system is unlikely sustained by magnetospheric accretion,especially in outburst. The accretion-related structures extend over severalstellar radii and, like the wind, are likely non-axisymmetric. The stellar massmay be $\sim$6-8 M$_\odot$, lower than previously thought ($\sim$16 M$_\odot$).Emission line analysis is found to be a powerful tool to study the innermostregions and accretion in stars within a very large range of effectivetemperatures. The density ranges in the disk and accretion structures arehigher than in late-type stars, but the overall behavior, including theinnermost disk emission and variable wind, is very similar independently of thespectral type. Our work suggests a common outburst behavior for stars withspectral types ranging from M-type to intermediate-mass stars.

Reading between the lines: Disk emission, wind, and accretion during the ZCMa NW outburst