My office has made great concessions for me, so I am unable to give you anything if your office requires "professional" shoes. There are, IMO, no minimalist or barefoot shoes that would pass as "truly professional"... for example, in a bank or lawyer's office or something that requires 'business' or 'business dressy' or 'highly professional' wardrobe. However, for myself, as a regulatory professional and medical editor at a major medical center, I have been wearing Vibram fivefingers Sprints in black, ZEMGear Playas in black, and Sockwa Dojos (grey/black and pink/grey--but I -am- a female) in the office AND for all of my "out of office" activites for going on 3 years, including riding my motorscooter, in Houston, in the middle of summer.
Hope that helps -- oh, and as for the heat issue... your feet DO toughen up over time. I had to stop letting my companion talk me into pedicures, because after a while, while I stopped getting huge callouses, I realized that the soft, sort of leathery feel to the bottom of my feet was a necessary part of my transition to being "less shod" -- what I DO NOT recommend, EVER, is going BAREFOOT on asphalt or any variant thereof in the summer in the south -- I learned that the hard way... Asphalt melting to the bottom of your feet definitely leaves very painful blisters!