Libre Office should already be installed too. What Desktop manager are you using? for any media file you want to play you need to install the codecs, these are different for Gnome and KDE. If you have Xfce and LXDE then use the same codecs as for Gnome.
YasT software manager is what you need to install more programs, However YasT doesnt looks like the Ubuntu Software Center, YasT is just a list of applications in the Software Center you can see screen shots and reviews of the application.
So, no there is no Software Center for OpenSuse, just YasT and you can also find more applications in the Package Search at this link http://software.opensuse.org/122/en
just type the name of the software you are looking for, search and download and YasT will take care of the rest.
Dont try to install files with the .deb extension because it wont work. Anyway Devede should be there but to use you need to install the CODECs first.
Good luck to you!