It will work, but yours RAM will work at lower speed, is safer to change your RAM to lower voltages.
You have this ones "G.Skill Ripjaws X Series" or "G.Skill Trident X" that work on 1.5V, this way you don't have any problems.
Yes it will, my laptop DVD driver stop working a few years. So I am using the external DVD player, without problem =)
When you plug the DVD player the windows will seek the proper drivers and install them =)
Yes you can buy Steam games with your Credit Card
Maybe this?
http://www.ebay.com/itm/Durable-25cm-3-5mm-3-5-mm-Stereo-Headphone-Y-Splitter-Cable-/151790754931?hash=item23576f1c73:g:URcAAOSwgQ9V2rIa
this put 2 headsets with the same sound