Dear Cristi,
Thank you for careful analysis and very important questions! I cannot ignore the issues of such importance. This will keep me busy for a long time. Thank you very much.
Responding immediately on the geometrization of the electromagnetic interaction I would evoke the Kaluza-Klein framework. However I have to study this question very carefully.
The holographic principle refers to string theories. These are also geometric in background but in completely different way. I cannot accept M theories as so far they do not generate predictions (there are some claims recently) and they demand more than 4 dimensions and I assume that 4 is enough.
I have claimed that the spin of graviton is not applicable as I am convinced (not in 100%) that gravity is not a fundamental but emergent phenomenon so graviton does not exist.
Not only your essay but also your honest approach and important notices deserve a high rating. I have not got my voting code yet. Guys responsible are out of the office.
Best regards,
Jacek