I don't think it's possible to run 3 car seats in the rear. I have two forward facing Diono's, which are on the slimmer side. There's barely any room left in the middle.
I submitted my claim a few days ago and received an email confirmation immediately. The confirmation says it could take up to 4 weeks to receive my check.
I had a W213 E63S. The car was amazing and the motor was intoxicating. The noise from the motor/exhaust will be one of the biggest things that you'll miss. You'll make up for the loss by getting instant torque and not paying for gas in the CT.
I didn't realize the BAT buyer fees were so high. It seems like BAT is better for specialty cars.
I'd prob recommend listing in the for sale section here, autotrader and cars.com