When using Color Management in Maya (2017), HDR maps should be set to RAW. More information can be found here.
A tutorial that uses the skydome_light can be found here.
The lights page has more detail about the controls. The only additional attributes are:
The skydome_light has a texturable color slot so that you can map a texture to be used for IBL.
The resolution attribute should be used with care. The higher the resolution value, the longer the skydome_light will take to pre-compute the importance tables for that light. For high-resolution maps, this can be very slow.
Note that 'Hardware Texturing' in Maya's viewport will only work when using a Maya file texture with the Ai Skydome light. Using an Ai Image, for example, will return black in the viewport.
The size of the sky in the Maya viewport.
The direction that the Color texture map faces in the viewport. Can be set to Front, Back or Both.
Currently, the skydome_light will not appear in the light linking window. A workaround is to use the defaultLightSet to change light linking options for Arnold lights (make sure to refresh the IPR when making changes in the light linking window). A video demonstrating this process can be found here.