Can you help me determine approximately how much it would cost per day to eat every single meal at McDonald's?

I was responding to this question and it got me to thinking about how expensive it can be to eat healthy, so I’ve decided to set a challenge for myself. Once I know approximately how much it costs to have every meal at McDonald’s for a whole day, I’m going to set a daily budget for myself to eat by and see if I can maintain a healthy diet on what it would cost to eat at McDonald’s for every meal.

In order to start, though, I am going to need to know how much it would cost to eat at McDonald’s for every meal in one day. You don’t have to figure out that number I know when to do my own heavy lifting ;) but I would like to know such details and in some cases, opinions as:

Should I include beverages such as coffee and soda?
What would be a good way to account for snacks?
Is it reasonable to include dessert in that or should I take the sweet stuff out of my established budget?
Would it be reasonable to make a few changes based on age, weight, and dietary restrictions? I’m a vegetarian

Any help with this is appreciated and I will keep you informed if you’d like updates. :)