...
In the RenderMan section of Maya's Preferences Window, you can choose whether IPR should use Image Tool (It) or Maya's Render View.
There is a separate display preference for preview rendering. "It" is the default for both preview and IPR, because it offers better performance and more features, but you may prefer to use a docked Render View panel for IPR.
IPR Camera
IPR and preview renders typically uses the camera from the active viewport panel. The popup menu from the IPR button also allows selection of a particular camera. The camera listed in the Render Settings window is used for batch rendering.
Select Object or Material from Render
...