Does SharePoint Server 2010 SP2 has also contains SharePoint Foundation 2010 SP2 updates ?

The answer is  YES

Unlikely the previous SP1s of the SharePoint If you have a SharePoint Server 2010 installation , just installing SharePoint Server 2010 SP2 is enough,
You dont need to install SharePoint Foundation 2010 SP2 first.

For more information about SP2 please check my previous article.
http://blog.bugrapostaci.com/2013/07/23/sharepoint-2010-sp2-has-been-released/