Question: Can I configure my files or directories in such a way to allow access to only certain directories on my disk?
Question: How can I enable a screen saver to automatically execute after a period of inactivity?
Answer: This can be done using regular Windows Display settings in the control panel.
Please do not forget, that when you lock your computer using public kiosk desktop, it will log in automatically under your controlling user, not under your usual user. Any changes to the settings you do for your locked mode, must be done under that controlling user, then they will be effective in the locked mode.