New ECM Help

Hello, our company is starting to implement a new ECM into our organization. We are a communication company with over 200 employees. Currently we are using shared drives and each shared holds approximately 25,000 files. We need to come up with a strategy on how we will run this process. All of these files need to be renamed, metadata needs to be extracted and added to docs/pdf?s/images, and about 20% of the files are duplicates. What would be the best steps to take to successfully complete this implementation?