Subtracting hours in a work schedule

Hello,
I am working on a monthly employee work schedule that has 2 stores. All employees work at both stores and the boss wants 2 separate schedules.
I have attached what I have started, which at the moment I am stuck.
I would like to have the Row 5 total hours to always reflect (subtract) a 30 minute lunch. I know it would be easier to have another column, but the boss wants it this way, UGH!!
I also need the total hours in column H to reflect the total of each day (with the subtracted lunch break). In this column I am having the figures turn red if over 40 hours and green if it under 40 hours.
With having 2 stores with the employees working at both, I need to somehow have the hours of the employees add up from one store to the other (a running total, if you will).
Lastly, if I have an employee not scheduled for a day or need to put other data such as, VAC, HOL or blank cell etc in a cell, how can I get this to work and not have the formula go nuts when it is not in a time format.
Thank you for any input anybody may have!