I have not heard of planting the leads in the spine. I'm doubtful of that since the DBS's purpose is to affect certain areas of the brain. Essential tremor often targets the VIM or the globus pallidous pars interna and their is a trial going on now I believe for the PPN which is for gait and balance control with PD.
The globus pallidous vs The sub-thamic nucleous target area has been double-blinded with the STN the winner for overall symptom control as I recall.

As far as the rechargeable batteries go, they are a great idea IF they work as advertised. I do not know the answer to that one. It is advertised as extending battery life to 10 years, which is great. The jury is (and will be out) for sometime on that one.
There is nothing new in this article.

Charlie