Thank you for writing to us. We value you as a Canon customer and appreciate the opportunity to assist you with the operating and features of your Powershot A495.
1. We would recommend turning off the Power Saving Function mentioned on page 43. The Power Saving Function will then have no affect on the screen shut off time when it is powered off. You will have to adjust the Screen Shut Off feature to a higher time like 2 minutes. I would also recommend checking to see if the Auto Power Down (p.104) is set to ON, try setting it to OFF. If this doesn't answer your question please explain what you mean by "defeat the shut off feature" when you have the option of setting the feature to the time of your choice.
2. I am sorry but it is not possible to use the zoom after you lock the focus using the focus lock feature. Remember that when you have the shutter button pressed halfway, the focus doesn't budge. If you ask your subject to move closer or farther away, or you move closer or farther from it to adjust your composition, your subjects no longer in focus. If the distance to the subject changes after you've locked the focus, let up on the shutter button and repeat the focus-locking procedure.
Zoom before you lock the focus. With most point-and-shoot cameras, locking the focus also prevents you from adjusting the zoom. If you want to zoom in or out after locking the focus, let up on the shutter button, adjust the zoom, and then lock the focus again.
3. You can remove the icons that appear around the border by pressing the disp button, you may need to press it more than once. It is not possible to get rid of the focus box.
I hope this information is helpful to you. Please let us know if we can be of any further assistance with your Powershot A495.