1. When did Nadd go to Korriban? My memory's sketchy here. Kun went there, that's true...however, Kun's main revenue of knowledge came from Yavin
Nadd didn't go to Korriban, it was an error there, but Kun definitely did. Revan also plundered from Malachor, and over 5000 years, it's hard to imagine it being possibly all protected. And it's even harder to imagine Sidious having it all.
2. I'll use the databank to help here: No one is quite sure how Palpatine was first introduced to the power of the dark side, or how he came to be Darth Plagueis' apprentice. He is the most powerful practitioner of the Sith ways in modern times. He studied the ancient ruins on the Sith mausoleum world of Korriban. He unlocked secrets of the Force from a captured Jedi Holocron. The dark side energies flowing through Palpatine's body were so intense, that they ravaged his mortal frame. The very source of Palpatine's strength was killing him.
In modern times. Dead giveaway there.
Kun, Sadow, Nadd, Kressh, Simus, Ragnos, Hord, they aren't exactly "modern" are they?
And yes, it does say he studied the ruins, but it sure doesn't say he knew all of their secrets or had all of their remnant artifacts. He also "unlocked secrets of the Force" yet got put on his ass by Mace Windu.
Clearly he is powerful, but he's not to the godlike level that the ancient Sith are. And the databank does nothing to prove he is either.
3. Well, for years of studying WITH the Ancients, having their artifacts, as well as whatever the New Sith of Bane's gang had, as well as using feats the Ancient Sith have not....
What feats did he use that ancient Sith did not have? He is never once (to my recollection) mentioned to have made a Sith artifact (like Sadow or Ragnos), he is never mentioned to have made a sith technique. He is recalled as the most powerful Sith in modern times, but the Sith were practically a complete nonfactor for a millenia, it's not like you've presented conclusive deductive reasoning to indicate he's superior.
4. If someone found egyptian scrolls, studied them religiously, learned all they could from them, learned at the feet of the finest pharaohs and warriors...
And he can beat them? Guys who fought for a living? You'd think that practical experience + immersive learning is more effective than just transcribed learning.
5. .....have you ever read Golden Age of the Sith, Janus? Sadow hardly ever expresses a view on anything minus "The Sith are absolute, we will conquer all." In between Dark Side sermons. The idea that the Sith were willing to follow someone so obviously murderous and ambitious, when one of their chief reasons for a war was avenging Simus...
And Hitler was all "The Arians are perfect, the Jews must die."
Not everyone followed him, but they ended up doing it when they felt they were wronged (a la the Germans feeling they were wronged following WWI).
And if you noticed, not all of them followed him.
6. Where was it even hinted Sadow created the ship himself? Could Bevel Lemelisk, say, have knowledge of how to destroy a planet as he helped design the Death Star?
It was mentioned Sadow created many powerful weapons, and the ship is always referenced as possessive, even by later individuals such as Kun and Aleema. Sure it's not absolute, but it's more absolute than "Sidious learned from a holocron." For all you know, he could have learned the Kama Sutra from there.
Bevel Lemelisk obviously had more advanced of a scientific knowledge than say... Han Solo.
Naga's ship was based on the force, he had to use the ship as a channeller of his force power. It's expressed when Aleema uses the ship also. Clearly we never are even so much as hinted that Sidious had the capacity to create that weapon.