Hi Nely,
1. You need to contact SAP-Ariba sales office or company who is having partnership with Ariba for OnCloud solution implementation.
2. You can have/import and use all your information from your current version of Ariba.
3. Difficulty and time for onCloud implementation depends on the customization your client wanted to have and complexity.
Hope the above answers your queries. Let me know if you need any additional information.
- Sourabh