Hi zizziz,
I believe each type of bath has it's own purpose, for instance, the body bath helps removes toxins or die-offs from the spirochetes (make sure the bath water is warm, not hot). And yes, you can use the salts and hydrogen peroxide for the foot baths too after doing a dry skin brushing on the bottoms of your feet. Each sole has over 2000 pores. I never used a machine foot massager though I'm sure it feels good!
The purpose of the cayenne pepper/mustard foot bath is to raise one's body temperature as a hot body is much better compared to a cold body because bacteria thrive in a cold body versus a warm or hot one. That's another reason people use sauna's. To sweat is a good thing whether it's from baths, exercise, whatever.
You may want to start charting your temperature: first upon rising, then in the middle of the day, then at night. If it's on the colder side that's not good thus that's where the foot baths come in handy, try it and take your temperature and see how much it rises.
Also, most pain is caused from toxins or the die-offs left in the body. If not detoxed properly, the toxins just get recycled right back into the body causing more havoc.
Hope that helps,
Denise