If I buy the ACIV Freedom Cry DLC will I be able to play it on my Xbox One? I noticed it's 9.99 on the xbox one marketplace instead of the sale price on the 360 marketplace.
Pretty sure it isn't cross-buy. The system you buy it on is the only one it plays on.
I think the Season Pass is cross buy at least for a limited time until May 31st of thie year. But the individual DLC is not. So if you just buy Freedom Cry then you'll have to rebuy it for the Xbone. But if you buy the pass you're in gravy for both systems.
Here's a link for the breakdown of various passes that are guaranteed to transfer: