There wouldn't be a portal in the nine hells, as devils embody Lawful Evil. The abyss would certainly have one however.

As far as magic goes, the key is the Elements and how they work together. If he could learn that he'd probably be able to get back to doing magic again. However there is nothing similar to demonomancy that can be done with RUNE's magic as it's impossible to bind a Demon/Devil to your will. Pacts can be made, but the other creature has to agree, one can't just summon demons to fight for them. 

What is true is that magic here is not 'Blood magic' so one does not need to 'cast from hit points' meaning it's a hell of a lot stronger here. 

He is definitely not the same as Orcs from this world, who cannot perform magic hardly at all. Lucky break for him though.

Regardless, I'd advise staying out of NOVA. 

Anyway, as long as we're clear on that feel free to post your CS in the codex.