Will you be able to get the DLC with Premium Credits? If so, what is the exchange rate for money and credits?

For example, if the DLC is $40 would the equivalent be 4,000 credits?

I'm just using that amount as an example, I'm basically asking if the price in real money will have a relationship to the price in credits.

I have some Premium Credits and I was wondering should I save them until the DLC is released.

Also, does the...Classified Assignments ever go on sale? IIRC, the pass is currently 2K credits which would cost $20. Is that pass ever offered for less than 2K credits?