Is excessive perspiration from the feet considered a problem?
Well, whether it is or it isn't. is there anything that can be done about it?!
I've obviously heard about the regular 'wear open shoes' 'let your feet air' theories, but at times we cannot help, but have to wear closed shoes.
Is there a medicine, if not, a powder one can use?

    

I think you have mentioned about the use of powder and that is a good idea to prevent bad odor from shoes.It is very difficult to solve this problem of sweating in closed shoes as it cannot receive fresh air and hence result in bad odor in your feet.You can surely try those open shoes but cannot really help you to solve your problem completely.

Is there something to do with material as well?
Are there certain materials available that help the feet 'breathe easier'?
I know that there are numerous advertisements to this tone, but how much truth do they hold?

Besides shoes there is one more factor and that is how much your foot are clean.
It is important to scrub your feet, each day at time of bath to remove the dead cells and then rub it with a fragrant moisturizing cream.Always wear clean socks and when shoes are not in use keep them in diffused sunlight to dry them and kill the germs.

I heard the only way to make it permanently go away is through surgery. Well, not so much surgery, I think. But they do something to the sweat glands. I think they inject hormones to lessen it. But don't take my word for it, it's just what I remember from someone else with the same problem.

Not sure if it is an actual medical issue, but I have a couple of suggestions. One is to examine they type of socks you are wearing. You want something that breaths like cotton, so if you wear nylon get rid of them. Also it could have something to do witht the shoes you are wearing. A breathable material is best or one with ventilation at least. Also it is helpful to have more than one pair so that you can either clean, disinfect, dryout the other pair to help prevent odor. These are just a few suggestions that help my spouse. Also if you work a desk job and can try removing your shoes periodically throughout the day to help keep your feet dry and cool.

Always wipe dry your feet before wearing your shoes. Aside from foot powder, there are also cream and ointment that can be applied to areas so that the sweat will not dwell in these areas.