The outgoing administration's November 2016 overview of HHS - weighing in at 122 pages - is still online at HHS.
It's a handy overview of the whole department, from the roster of presidential appointees (Surgeon General, Head of NIH) to the healthcare spending and the "discretionary" spending (e.g. NIH, FDA).
HHS expected to have 76,342 employees in 2017. An Org Chart of HHS is here. Dr. Don Wright was the Acting Secretary briefly in early October; replaced by Eric Hargan on October 10 (here). Jeffrey Davis is Acting General Counsel, here. Randy Pate heads CCIIO, which oversees many aspects of the Exchanges.
The current surgeon general, Vice Admiral Jerome Adams, took office on September 5, 2017 (here).