Hi Neeraj Srivastava,
Please check following two notes for question 1:
543821 - FAQ: Cross-company processing
308989 - Consulting note for cross-company transactions
These two notes explain related customizing and frequently asked questions regarding intercompany process.
Then for question 2, please check note:
38501 - Intercompany billing before customer billing document
Hope I was able to help with above information.
Best regards,
Crystal Lin