Production Scheduling

Okay, I have quite a project and I don't know where to start. I wanted to talk to the fine geniuses at Excel Forum to see what recommendations could be made. I am posting this in the programming because I am pretty sure it's going to take some advanced level stuff.

There is a desk sharing initiative where right now maybe we have 90 desks and for the most part everyone has their own desk. However we are noticing there are maybe 30 people at most ever working at one time. So in order to save money and give the space to other needed projects we are doing a desk sharing project. We want to be able to say we have 70 people working in office on this day and we only need 30 desks (1st, 2nd, 3rd shifts- 24/7 business). So I have an export of schedules that have the employee's name, and EE#, it has the date, their start time, and end time. The export covers a week projection but schedules are always changing based on the needs of the business so I need to be able to replace the export with a new one and have a new calculation take place. I would like to be able to paste in my export and then it assigns desk. Desk 1 will have employee 2 from 10PM - 6AM, employee 66 will have the desk from 7AM - 3PM, and employee 98 will have the desk from 4PM - 10PM, employee 25 will have the desk from 12AM - 7:00AM...etc. Attached is an example export. I need to be able to manually adjust the buffer of 1 hour to whatever the user selects. I also need to somehow over write the assignments, there are always people who should sit next to each other and I need to be able to move people. Thinking about something really cool, the ability to maybe drag an employee to a desk and it will assign desks around that? First the basics, then I can hammer out the specifics. Any help is always greatly appreciated.
Schedule%20Export.xlsx

You should probably just explore some free (http://www.kappix.com/) or pay for use shift scheduling software. This would be a nightmare and take a while to program in Excel.