Can I use chain rings that were on a 9 speed for my 11 speed cassette or do I need to get 11 speed chain rings?
Max length chain you can get: 500 foot from here http://www.bikeman.com/CH5052.html ... should be enough :D !
You may find shops reselling whatever length you want.
A 11 speed chain should work okay on 9 speed chainrings.
Keep up with frankenbiking, the fun is in the process and in the final result!