Process

I found this link really interesting. It explains the process and production of 'Frozen'. It explains that although it is based on the Hans Christian Anderson novel 'The snow queen' it only takes a few bits from this like the ice and the queen. The entire rest of the story is completely different. It also explains reasoning behind decisions and what was difficult and easy like creating a character (Olaf) that is able to split into 3 pieces and put itself together was an interesting task.
This part parrticularly made me giggle but I can understand why they did it!-
'Like all of our films, research was a big part of out process. With our animators living in California, we needed to send them to Cheyenne, Wyoming so they could experience what walking through deep snow is like. They actually did it in dresses – the guys did it in dresses to – in order to get a sense of what it would be like for our heroines to traverse the snow.' 
This peice really helps you get an insight into the work that goes on behind the scenes in the making of disney movies.

http://www.bleedingcool.com/2013/09/25/inside-the-research-design-and-animation-of-walt-disneys-frozen-with-producer-peter-del-vecho/