Re: screen saver
It is relatively easy to turn off the screen saver in Lubuntu. Go to Menu->Preferences->Screensaver. Under Display Modes, change the Mode to Disable Screen Saver.
You can check for updates manually using Apt-get, Synaptic Package Manager, or Software Updater. Conversely you can allow the system to update itself. Launch the Software Updater and then navigate to settings. Under Updates you can choose when you want to update.
ASUS EeePC 1000h with Lubuntu 14.04 and Lubuntu 15.04
Dell Inspiron 1000 with Lubuntu 14.04