Sorry for the late response. The answer is yes for the soaking. And though I realize your infections may have been dealt with, I figured it may be worth mentioning it in the unlikely event that you might have to deal with this again.
On the matter of the blood purifier, I'd add that though this technology was devised to purify blood first and foremost, that I've discovered that it can also be used in other ways. ie. in my own case, I apply an electrode on each side of my jawbone(side and under) so as to encapsulate or sandwich the jaw bone which in turn allows me to apply an electric field right through the bone. To which I'd add, has proven to be quite amazing in terms of dealing with the infection to say the least.
That being said, I'd also add that the blood zapper is quite a remarkable device in terms of dealing with blood-born infections(sepsis)also. Which I've had the pleasure of using a number of times during the course of my own trials.
As for where on the body the zapper might, this will likely depend on such thing as the depth(tissue etc) of the area and strength of the machine. Though I've experimented with placing TENS pads(silver/carbon type) on my abdomen and back area(across from each other) which felt very much as though the electrical field was crossing my entire body. And so I'm really not certain as to the limitations of the unit in this regard, but this was what I found using my home made unit powered at the maximum voltage for the circuit(30v).
On the issue of medication interference I'm afraid I cannot say given that I haven't combine my treatments with anything other than Antibiotics that were given to treat a nasal infection and had no effect on anyways, and so not much information there I'm afraid.
On the topic of Colloidal Silver , I make my own using 3 batteries, a 2.4mah current regulator diode and some 10ga silver rods. And I do it this way for a couple of reasons. 1) I tried using the best Colloidal Silver on the market and it didn't work AND 2) it's much cheaper than buying(Spent over $400 buying CS).