We investigate the properties of the interstellar medium, star formation, and the current-day stellar population in the strongly lensed star-forming galaxy H-ATLAS J091043.1-000321 (SDP.11), at z = 1.7830, using new Herschel and Atacama Large Millimeter/submillimeter Array (ALMA) observations of far-infrared fine-structure lines of carbon, oxygen, and nitrogen. We report detections of the [O III] 52 mu m, [N III] 57 mu m, and [O I] 63 mu m lines from Herschel/PACS, and present high-resolution imaging of the [C II] 158 mu m line, and underlying continuum, using ALMA. We resolve the [C II] line emission into two spatially offset Einstein rings, tracing the red and blue velocity components of the line, in the ALMA/Band 9 observations at 0 ''.2 resolution. The values seen in the [C II]/far-infrared (FIR) ratio map, as low as similar to 0.02% at the peak of the dust continuum, are similar to those of local ULIRGs, suggesting an intense starburst in this source. This is consistent with the high intrinsic FIR luminosity (similar to 3 x 10(12) L-circle dot), similar to 16 Myr gas depletion timescale, and less than or similar to 8 Myr timescale since the last starburst episode, estimated from the hardness of the UV radiation field. By applying gravitational lensing models to the visibilities in the uv-plane, we find that the lensing magnification factor varies by a factor of two across SDP. 11, affecting the observed line profiles. After correcting for the effects of differential lensing, a symmetric line profile is recovered, suggesting that the starburst present here may not be the result of a major merger, as is the case for local ULIRGs, but instead could be powered by star formation activity spread across a 3-5 kpc rotating disk.