I'm also curious about these.

What I am also curious is around memory management. On the Intel, I can get at most 64Gb RAM for now, 96Gb in the future. On AMD I can get 128Gb right now. Do they differ in how they can share RAM with the GPU? Do either need me to specify how much is vRAM and how much is available to the CPU, or are them both unified, similar to how Apple Silicon does it?

for the current moment, Intel seems to be ahead of AMD for both power efficiency and iGPU performance. Panther Lake is really, really good.