Thank you for responding, first of all! I feel like I should note that the goal is more to make him optimal within his sphere, rather than the one true sorcerer. I just like the thought of having a full plate "arcane" caster.

1. From my reading, yes - all sorcerer spells & SLA's are treated as if they were psychic in origin, which also leads to the Intimidate kryptonite. Hence, I'm thinking about going Half-Orc for the Unflinching Valor racial trait, giving +2 vs fear effects (which Intimidate should be), and with Unflappable Arrogance I believe I'm sitting at a DC 17 before adding any other modifiers into the equation.

2. The VMC is debatable, I understand that. Since my overall goal is just really to have a full plate casty that slightly subverts expectations, would you then recommend just getting the feats the old-fashioned way?

3. It's a mixture of all of them