The first and probably most important prerequisite for a successful merger or acquisition is that you have a complete and well-defined future brand and value proposition for the resulting company. Next, you should perform a thorough due diligence process, not only looking at financial and contractual obligations, but also at the enterprise architecture focusing on business processes and the application portfolio, maybe with even more scrutiny.

Yes, certainly CobiT can help with cloud-computing.

CobiT is an IT governance framework and particularly two processes "Define a Strategic IT Plan (PO1)" and "Manage Third-party Services (DS2)" will give guidance on what you should do before and after selecting a cloud solution, how you could measure and monitor the value you gain as well as your risk exposure and who should be responsible, accountable, consulted and informed during the effort.