Hi Kesa_Kara,
If you have already created the account in Office 365, you should use SMTP matching to match on-premises user accounts to Office 365 user accounts for directory synchronization.
Please refer to the following link for the detailed steps:
http://support.microsoft.com/kb/2641663
For the Dirsync, the attributes in the following article will be synced from on-premises to Office365.(the on-premises attributes will cover the attributes in Office 365), here is the link:
http://support.microsoft.com/kb/2256198
The latest Active Directory Sync tool support the password sync feature, you can refer to the following article:
http://technet.microsoft.com/en-us/library/dn246918.aspx
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Single sign-on (SSO) allows you and your users to access Microsoft cloud services with your Active Directory corporate credentials. SSO requires both a security token service (STS) infrastructure and Active Directory synchronization.
When you set up and enable single sign-on (SSO), users in your organization are able to use their corporate credentials to access the Office 365 service offerings. This removes the burden of managing multiple logon identities and passwords. Without SSO, an Office 365 user would have to maintain separate user names and passwords.
Here are the links for the Single sign-on roadmap:
http://technet.microsoft.com/en-us/library/hh967643.aspx
http://technet.microsoft.com/en-us/library/jj205462.aspx
Thanks,
Jason Jiang
