I am sorry to hear about your accident. But I am glad to hear you are not seriously hurt.
With your car. Who is your insurance company? Last year I got into an accident and the whole passanger side had to be reconstructed, the bill was about 10 grand, this is for a 92 300D 2.5 with 275,000 miles ?? or so at the time. Anyway, they fixed the car and did not total it. So since your car is a 400 and has less miles, maybe they will fix it and not total it if its over 7 grand? This varies with insurance companies so I cannot answer that question.
As far as the car is concerned. Do you really want it? Cars are not the same after an accident, at least from my experience and others. I had mine fixed at the dealer and now there is still wind noise that can be heard in the cabin since the accident. If you have frame damage or worse, it might not be the same anymore. Please dont let me discourage you or anything but I am just giving you a warning.