Kamal,
Layouts are different for each bridge type that has been supported over the years in TMS. Therefore, device-specific configurations like layout, have not ever been included in the Booking API. The Booking API is meant to abstract away as much complexity of how SIP, ISDN, H.323, bridge resources, availability, etc., therefore the API client does not have to understand all things videoconferencing or telepresence.
In regards to CMR Hybrid (WebEx Enabled TelePresence,) TMS automatically populates the WebEx user from AD Lookup using attributes from AD. In this particular case, TMS is using the Windows AD Username (samAccountName) attribute, but could be Email (mail) or any other custom attribute.
When using the SaveConference, SaveConferenceWithMode, then add either the <DataConference> to [Yes] or [If Possible] or use the <ExternalConference><WebEx><TmsShouldUpdateMeeting> to "True". TMS will scheduled the DataConference/WebEx meeting automatically using the Booking Owner's stored or retrieved WebEx username stored using the WebEx Settings.
Michael