What is your question concerning BOINC?
As for power settings, try Power in System Settings. In order to enable hibernation, see here.
For screensavers, look in Brightness and Locks. If you want fancy screensavers, then install xscreensaver and the screensaver packs:
Remove packages that you deem unnecessary from the list. Then remove gnome-screensaver completely and add 'xscreensaver -no-splash' (no quotes) to Startup Application.
sudo apt-get install xscreensaver xscreensaver-data xscreensaver-gl xscreensaver-data-extra xscreensaver-gl-extra xscreensaver-screensaver-bsod xscreensaver-screensaver-dizzy xscreensaver-screensaver-webcollage