For tarball releases of HarfBuzz, look here. At the same place you will also find Win32 binary bundles that include libharfbuzz DLL, hb-view.exe, hb-shape.exe, and all dependencies.
The API that comes with
not change incompatibly. Other, peripheral, headers are more likely to go
through minor modifications, but again, will do our best to never change
API in an incompatible way. We will never break the ABI.
If you are not sure whether Pango or HarfBuzz is right for you, read this.