The voltage won't be a problem.
The auto setting isn't too consistent. You can try calibrating your setup to tailor your exposure to a particular flash setting and combination of camera and lens settings, but it can be frustrating. Sometimes the results are better than the TTL of a dedicated flash, other times not. This may be because I've exceeded the capabilities of the flash.
I would suggest you set your camera to Manual with shutterspeed of 1/(lens focal length) or higher and aperture of f/5.6.
Slide the flash switch on the back at the left up to the M (manual) setting, and then you can adjust the output from full power down to 1/16. The lowest power can still be too high in some circumstances - you can use a piece of paper, a Sto-Fen diffuser or Sunpak's ND filter and/or wide angle diffuser from the dedicated filter kit. Set the ASA slide switch to your camera's ISO setting and you'll get an indication of the flash range for f/stops at the different power settings. That's with the flash head pointing at the subject with no modifier and the range will be less when you use ceiling bounce.
Then it's a case of taking test shots until you get acceptable results. Shoot RAW and fix with post processing if you can't set things up the way you want in the time available.
Open the battery compartment and you'll see a bright metal latch. Pull it out by a few millimeters and you can remove the flash foot. It's not really worth getting one dedicated to your camera but the STD-1D type has a small jack for a sync cord (get the right type from e.g. FlashZebra.com). The Sunpak EXT-10 cord will allow you to hold the flash off-camera. It's also got a 1/4-inch tripod socket and is the most reliable way of hooking up a radio trigger, which can hang by the cable or be strapped to the flash.
