True about frenemies the entire time that Apple was suing Samsung, it was using Samsung to manufacture many of its components.
Since they're not branding it as ARM in any way, shape, or form, and they have a perpetual architectural license to the ISA, I suspect they could do pretty much what they please - as long as they don't call it ARM. Which they don't.
Even if not, then yes, I would imagine that a behemoth of IP design like Apple would probably have considered IP rights during that design...
Yea, they got fucked by Nvidia business practices multiple times. There's a saying about shame on you, shame on me, etc. Unless the entire Nvidia business unit also gets replaced in the same transaction, it doesn't matter how much of a faux separation of concerns they want to market.
Just because Apple and nVidia has bad relationship at the moment regarding their GPUs is probably orthogonal to what they'll do with this new branch of nVidia, that is ARM.