My new Mini comes with the internal power supply and the cord that comes with it is too short. Is it safe to use an extension cord with it?
Also, is there anyway to turn off the start-up chime? I have headphones plugged into it and with my older Mini as long as I did that I didn't hear the chimes.
Last, what happened to the up and down arrows to navigate? I usually use the mouse scroll wheel but my mother can't because of carpal tunnel (she got my old Mini).
You can use an extension cord however personally I would not. I would however recommend getting a UPS (Uninterruptible Power Source.) You can find them at your local office supply store, Costco, Best Buy or local computer store. A much safer solution and it offers an additional layer of protection for your computer investment.
Regarding the start up chime, there are utilities for turning it off. You can find them by doing a Google Search however once again I'd recommend against it because the chime is an important part of the startup sequence. That being said why are you turning off the computer, please read your owners manual! If you insist on shutting down your computer rather than letting it sleep then simply turn down the sound prior to shutting it down.
In the current version of OS X Lion Apple has removed the scroll bars, You can turn them back on though in System Preferences - General - Show Scroll Bars. Lion is new and it's different, some things you may like some you may not. I would recommend reading MacWorlds review on it at:
http://www.macworld.com/article/161026/2011/07/osx_lion_review.html