I'm so, so sorry for what you are going through.
I found myself in a very similar situation a couple of years ago, and also ended up having a surgical procedure, although I didn't have placenta previa.
I was told by the hospital that only a few of their consultants are able to carry out the procedure after 16 weeks, so I would imagine it is highly likely that you'll get a skilled consultant doing this, and therefore will be in good hands.
Have you been appointed a bereavement midwife? If so, it would be worth asking her if you can get the name of the consultant and also have a meeting with them or the surgeon beforehand to find out more about the procedure.
They talked me through it all on the morning, but my head was such a blurred mess by then that I didn't really take it all in.
I would also highly recommend speaking to the charity ARC - www.arc-uk.org/
They have amazing people who provide information by phone, and can also add you onto their closed forum board, so you can speak to other people who have been through it, and will be able to answer some of your questions.
The one thing that no one warned about was that my milk would come in after the procedure. It was about 3 or 4 days later and was totally horrific, so I would also be prepared for that, and speak to the hospital about getting a prescription for Bromocriptine, which will help stop it.
Please feel free to PM me if you want to 
Wishing you all the strength for the coming days, weeks and months