On 2), I envision that 100% of the hypothesized 20% royalty on Amphastar’s sales goes to MNTA. The patents in question belong to MNTA, not the NVS/MNTA JV; moreover, post-2014, NVS benefits indirectly by keeping a larger proportion of the NVS/MNTA JV’s profits.
I agree with the 100% to MNTA, but based on your second argument.
NVS does have an exclusive license on the patents, thus the fact that MNTA owns them does not matter.