Migration to Cloud IT and the management and preservation of 'legacy data'

We need an independent IT consultant for a second opinion. We are a small firm that is planning to migrate to cloud based services, looking for advice including but not limited to below questions:

1. Which cloud system is the most suitable for our firm? In terms of service charge, stability, efficiency, cost and security?
2. How to preserve our database (probably unsuitable for migration to the cloud)?
3. Review of current hardware and software and its compatibility with a cloud system
4. What other equipment do we need to buy/ software to install to meet the requirement of the cloud system?
5. How to train our staff to use the new cloud system? Does the cloud system provide a user-friendly manual, any online chat/ email inquiries available?
6. Anything we need to pay attention to when we migrate to the cloud system?
7. How long does it take from start to complete the migration?
8. Are you available to come to our office to provide advice in person with a written report thereafter?
9. Which system will best meet our needs for security and remote working?
10. What are the pros and cons of moving to cloud systems?
11. What back up systems are available to save cloud data in a worst case scenario?