The mist in between the glass is caused by moisture getting in the window. This indicates the seal on the outer edge has been compromised ether due to deterioration or physically damaged ether case I believe the windows have a vacuum or dry gas in-between the panes before the seal is completed. So to answer you second question I don't believe that you can correct this problem your self. I have brought panes of glass and windows to my local hardware store in the past and they were able to send them out and get them redone. So the diy part would be the removal of the glass to send out and get redone. I would suggest calling around before removal though to make sure you have known time frame that you will be without you glass, also maybe only do one at first to help discover any surprises that you might run into in your situation.