Compatibility Questions - FP10, CS4, AS

I am using Flash CS3, programming AS3, and targeting FP9 for the moment. However I am seeing references around this board to FP10 and CS4.

My questions:

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[]On the Adobe site looking at CS4 features, I’m not seeing any changes to ActionScript. It seems to be mostly 3D stuff. Is this the case?
[
]Do you need to develop in CS4 to target FP10?
[*]Even if you don’t need CS4 to target FP10, do you need it to take advantage of new functionality in FP10, or can that be done with CS3?
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