If you want you can try OnlyOffice, it works really well as a replacement for Office. That is if you only use Word, Excel and Powerpoint. I even convinced some Windows people to use it as its free, open source, cross platform and perhaps even easier to use at this point.

For Picasa maybe digikam? It maybe isn't a perfect replacement though. You could always try to run Picasa in a VM (or maybe even wine?)