2. Is it at all possible to walk him in the am and then while you are getting ready to leave, that's when you could feed his morning meal?
As far as him being ok all day without using the bathroom that depends on how long your work day is...for example, mine is 12-16 hours, which would never be ok for any dog...but luckily he comes to work with me where he gets walked at least 2 times a shift.
I could feed him after the morning walk, but with our time schedule he would go in his crate right after. My work day is 9 hours total (including the commute and lunch break).