So, I really don't have much to add to those points except for a few things here:

-The Rakata certainly seemed like(for the most part) a people consumed with attempting to establish dominance over anything(or one) that they come into contact with. Naturally then whatever survivors from the Infinite Empire were left on Lehon would be po'ed that Revan kinda tanked their whole Star Forge operation because of their desire to exhibit power over the galaxy. This desire stems from Valkorian...

-...who ran the Eternal Empire out in the deep fathoms of Unknown Space(KOTFE never explained that very well, did they? At least, I haven't received an explanation up to where I'm at now, which is chapter 12? I think?) and utilized many of the same techniques Renso became aware of in his little corner of space thanks to the teachings of the True Sith. I'd like to think that Valkorian discovered how to manipulate the Force to preserve himself from Sith who he then killed(that sounds like him, doesn't it? xD) to try and preserve the secrecy of his powers, which of course didn't work thanks to the True Sith establishing themselves far enough away from Valkorian to escape his notice. Right, so back to Val. 

-Val builds up the Eternal Empire, which naturally catches the attention of the Rakata, who attempt to wage war with their own Infinite Empire. Naturally Val is intrigued by how the Rakatan can exploit the Force for their own galactic domination, so he allows for skirmishes to occur while intelligence is gathered about their new opponents. After sufficient recon, Val "surrenders" and allows the Rakatan leaders to unbridled access to the capital city. With the Rakatan's guard down, Val's military forces seize the various weaponry the Rakatan have along with their leaders, who Val promptly tortures in order to extract information(because, again, it's Valkorian). The torture doesn't last for very long, however, seeing as the Rakatan leaders aren't morons and know when they have been defeated, so Valkorian's Eternal Empire and the Rakatan's Infinite Empire strike a deal. The Rakatan fork over their knowledge and blueprints to the Eternal Empire while being given the support of the Eternal Empire to go out and subdue the unknown regions of space. This then sparks the Rakatan invading known space and establishing their hold over known space until infighting(of course) broke their empire down and so on. 

-Fully aware that the Rakatan would eventually consume themselves, Valkorian bides his time, constructing more Star Forge type machinery and consuming more and more of his sector of the galaxy until all of it can be claimed as a part of the Eternal Empire. From there, he launches a campaign into known space and establishes the Empire, disguising himself as the Emperor and eventually is killed by our boy Voldon. Although his body is gone, his spirit remains painfully alive and is currently guiding his son, Arcan, to amass enough of a force to finish what he started. The Eternal Empire's potential dominance over all sentient life is the threat Revan sensed all those years ago and recruited Meetra to help him with.