Apologies for the delayed answer. I am overbusy at the moment... :)
I don't buy quantum inertia at all, because it violates several pillars of modern physics in many ways (special relativity, general relativity, Noether theorem, Newton laws of motion), and those pillars have been heavily tested experimentally (and found correct). A little bit too much of basic physics violation to my taste :)
For more information, feel free to read this that is a very good article on the topic.
I will now answer the questions (or instead to ask questions about the questions), ignoring the QI part because I don't have time for that. Note that I am happy to work on speculative theories, but not when they violate many basic principles and are supposed to solve so many problems including non-problems.
What happens to a pair of virtual photons that form in space that is expanding faster than light? E.g.: one photon forms opposing the expansion, while the other forms with the expansion.
Virtual photons are not real. So nothing :)
Can dark matter become a black hole? Since it only interacts gravitationally with ordinary matter, is it possible that the first “visible” indication of dark matter is x-rays from the accretion disk of a black hole? In fact, since most matter in the universe is supposed to be dark matter, wouldn’t that imply that most black holes are formed from dark matter?
Black holes are candidate for dark matter. So they can be dark matter. However, dark matter can't for black holes as it is too diluted in space. In addition, it is good to note that black holes can absorb dark matter, as normal matter.
Is unruh radiation light?
Radiation is photon.
Ps: the pilot-wave theory does not violate basic physics, in contrast. It describes quantum mechanics slightly differently (in a way that cannot be falsified for now).
As near as I can tell, physicists worth their salt look at the math of QI and literally see flying saucers because QI asserts that gravitational mass is not equal to inertal mass.
I believe the only thing pilot-wave doesn’t explain very well is quantum teleportation.
Thus, its funny. There are two things Einstein said, mass equivalencies (against QI) and spooky action at a distance (for pilot-waves), that are both in play.
For this reason, I think Einstein would doubt QI and lean toward pilot-wave, not that they’re at odds with one another or anything.
This is weird, as the equality of both masses is not a fact. There are many experiments trying to proof both masses are inequal. For now, they only have managed to demonstrate that the inequalities should lie at the 14th digit level, if any (see here for instance).
The pilot-wave interpretation relies on a non-vanishing potential at infinity. This consists in a very non-intuitive thing.
Somehow, it does not like the non-locality behind quantum mechanics, and get rid of it in a way closer to classical mechanics at the price of a potential,... that is non local. Therefore, all the non-intuitive aspects of quantum mechanics are still there. At the end, only data will tell us on which one (the quantum mechanics or pilot wave interpretation) is correct. For now, both agree and there is no way to disentangle them. If interested, I may try to free some time to write a full post about that (I discuss this topic in my book, but it is in French :p )
The EPR paradox has been solved since them (cf. Bell inequalities) and there is no spooky action at distance (this is proved and well established). This contrasts with pilot wave interpretation that is neither proven correct or wrong.
But alpha radiation is helium nuclei. Is it just a misnomer?