RE: Importing contacts to Outlook 365 via Yahoo_contacts.csv

You can sync any external data (including CSV based contacts) to Office 365 (Exchange or SharePoint) or with MS CRM and almost any other Tools using 3rd party sync tools like this:

http://www.layer2solutions.com/en/community/FAQs/cloud-connector/Pages/SharePoint-Exchange-Integration-Provider-Specification.aspx

The article is just one sync sample. Follow the links on the site to find more, e.g. how to use CSV:

http://www.layer2solutions.com/en/community/FAQs/cloud-connector/Pages/Text-Sync-to-Office365.aspx

Thanks, Frank