Miles plus cash

This might help a little, KLM and Air France aren't just partners, they are the same airline. They merged operations a few years ago. For the time being they still operate separate fleets. But in terms of FF miles, there is a chance they might be interchangeable; but I don't know the precise answer. Your best bet would be to call KLMs 800 number. But there isn't much you can do with 9000 miles; at least for transatlantic flights.

Your FF miles can only be redeemed via KLM, but the KLM Frquent Flyer department can redeem them for you on other airlines, especially AF.

Some airline FF depts have a Miles plus Cash option and that can extend to flights on other airlines. The only way you will know is to call KLM's FF agents and get their advice. The only problem is that KLM may have a minimum amount of Miles required for a Miles plus Cash transaction.

Yes - definatley call KLM or AF and ask for details. However, be prepared to find out that you may need more like 30-50,000 miles for international. I use lufthansa and they have a 50k (47k on the web) for economy reyutn trip, as well as 90k for business. They do let you buy missing miles, but only up to 15k. Depending on when youre flying, you may be able to just pay a regular low-off-season special and rack up more miles for another trip. In the mean time - get one of their FF club credit cards and use it where evere you can (just pay it off fast so you dont also "earn" too much ininterest fees - you want the miles!!) They may have a special 20k sign up bonus too which will help you reach a free ticket faster too.
One more note - in peak season flights, you may need to book 10-11 months in advance to secure that free seat. demand is high and free seats are few!