Sort Employees in Roster

Hi so I need to do a roster for 9 shops in separate locations, and everyday there need to be 20 people working out of 42 employees.

What I would like to do is for every shop I want to roster individuals that live closer to the shop, then if there is no one close to the shop I want another random person to be allocated to that shop.

At the bottom of the excel sheet I want a total of individuals that are working that day in that particular shop. Then I want all the roster to firstly be displayed as something similar to Sheet 2 and then to be displayed something similar to Sheet 3

I know that this is quite complex but I think with your help I can manage.

PS. the "shops" that I am doing the roster for are food banks, and the "employees" are volunteers. WE are not getting paid to do this, but I want to make the process easier.