The quick and dirty answer for iontophoresis helping with plantar and palmar hyperhidrosis is: YES it does effectively reduce the symptoms.
To answer your questions:
1. Home made is my only experience. However, for the results I have achieved with it, I don't need to spend the money on a name brand machine. The important part is adding salt (for more conductivity) and baking soda to the water bath. You don't have to turn the water bath into the Dead Sea. I would guess I use about a tablespoon of salt and the same amount of baking soda. Again experiment to see what works for you.
2. I use aluminum pans and place them in a cheap metal pan for support. You could also place aluminum pans in a plastic pan too. Just be sure to clip the test nodes to the aluminum pans (that should be obvious).
3. Time is related to the amount of sweat you produce. I suffered from severe plantar hyperhidrosis and I typically do 30 minute maintenance sessions (15 minutes and then reverse the direction of the current for the remaining 15 minutes). My initial sessions ranged from 30 minutes to 1 hour.
4. I did it every day consistently for 2 weeks and then switched to every other day. Now its been 4 weeks and I continue to go every other day. Soon I will start scaling back by one day and wait for the breaking point to occur.
5. Voltages vary. I really recommend investing $80 or more for a AC to DC power converter with adjustable voltage and avoid batteries. I paid $90 for mine and would recommend it for everyone who is looking for help with HH. When I started off, I did 24 volts DC for more than 30 minutes. That caused a small blister. My sweet spot is 18-19 volts. This is why I say go for a DC power converter with the capability for controlling voltages.
6. I try to keep my feet elevated enough so that they don't touch the bottom. There isn't any harm in having them touch the bottom, but you want to have space so that the ions can migrate easier into the skin.
You will experience stinging or tingling sensations. It is similar to placing your tongue on a 9 volt battery. My recommendation is using vaseline or Aquephor lotion on your nails and cuticles. That stuff is non conductive and will stop the current from going into those sensitive parts. If you have a cut or an abrasion, throw some of that on there too, or you will feel a decent sting on the cut if you don't use it.
Another side effect you may experience is itchy skin. It's a small sacrifice for bringing HH under control.