1.Yes its possible to use the iCM script only. you can use ICM micro app. Micro-applications are a set of specific IVR functions that can be invoked by Unified ICME, enabling communication with the caller.
refer this link, it will help you writing script with micro apps.
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cust_contact/contact_center/customer_voice_portal/cvp10_0/feature/guide/CCVP_BK_FA976D84_00_feature-guide-for-cisco-customer/CCVP_BK_FA976D84_00_feature-guide-for-cisco-customer_chapter_01.html#CCVP_TP_M968839E_00
2. What is the exact use of CVP scripting and when it is used parallel with ICM scripting.
Sophisticated IVR applications can be developed using Call Studio. This is an Eclipse-based service creation environment whose output is an intermediary file which describes the application flow. That file gets loaded onto the VXML Server machines for execution. To invoke a VXMLServer application, ICM instructs the VoiceXML Gateway to interact withthe VXML Server directly to execute the application. Final results are then passed back to Unified ICME.
Among its many features, the VoiceXML scripting environment has a drag-and-drop interfacewith a palette of IVR functions, can do database queries, and can even be extended with Javacode written to perform any task a Java application could perform.
But ICM scripting is used to develop agent routing scripts, and to invoke Unified CVP micro-applications—basic building blocks of a voice interaction design. The Unified CVP micro-applications are Play Media, Get Speech, Get Digits, Menu, Play Data, and Capture.
Micro-application-based scripts are primarily used for initial prompt and collect operations, as well as for directing the playing of .wav files while calls are in queue.
3. Once we enter to the call studio for CVP scripting how the CVP scripting call flow is taking place.
It will execute each node you have implemented in CVP script and once the script is done it will return the value to ICM.
Example:
Audio node will play the wav file you have configured in this node.
Menu Node for menu option.
