I had ECT about ten years ago, so my response may be a little out of date, but I remember being given some ibuprofen right before I went in for my treatment and it helped with the headache. Not sure if your anaesthesiologist will allow it, since you have to take it orally, but it didn't bother me any. I didn't have any progressive memory loss, but did have a little short term memory loss just during the time I was receiving treatments. I had mine on an inpatient basis and my treatments were unilateral. Memory loss tends to increase with bilateral treatments, so if you're having electrodes on both sides, you could have more memory loss. And I think 12 treatments sounds about right. I was on track to have 12, but only had six because it worsened my dissociation.

I hope you find the treatments helpful and have a quick recovery.