Hi.

1) There are many medications out there. Benzos can be highly addictive. However, that being said, they are also extremely helpful. I have used them for years for sleep and as anti-anxiety medications. You could try a Benzo with a longer half-life, so that you are only taking it once or twice a day. This perhaps reduces the chance for addiction.
Additionally, some of the newer anti-depressants also have the ability to reduce anxiety, including Lexapro. The mood stabilizer (actually it is a seizure med) Lamictal appears to also help with anxiety.

2) SI scars. Have you tried wearing gauze-like long sleeves over a nice summer blouse. I have the same problem, where my scars are all over my arms. Fortunately, I wear jackets and suits to work everyday, and a med coat over it. But when I am outside of work, I try and find lightweight material like gauze to wear.
If your scarring is bad, it is best to cover it. Especially, just starting a new job. It would probably cause more issues about your health than you need right now.
I am surpised that the plastic surgeon said that you could not be helped, because they do skin grafts on "burn" scars that are years old. Surgeries of that nature can take years.
I would get another opinion. They may not be able to do laser surgery to remove the scars, but there should be something that can be done. (It might cost more).
Also, usually surgeons will NOT do anything unless you have stopped SI.

Good luck with your new job.