If you have a look into file thesis.tex located in your given link you can see that this thesis.tex fullfill the requirements.
12 pt type means the size of your font for normal text in your document. LaTeX builds the headings with greater fonts automaticly. With "double spacing" is a special distance between two lines of text ment. Have a look to the question marked as duplicate (David Carlisle mentioned it in a noe deleted comment).