Now, I haven't read the novel (though I desperately want to) but I've heard that provinces get secede and over run. What causes them to do that?

No central figure to hold the legitimate violence. And because that central figure that was mostly stopping each province from killing each other is gone, those provinces are now letting old wounds get to them. The altmer are trying to rebuild their Aldmeri Domain, drive the men away, and move backwards (which shall never be accomplished). The mane has been assassinated, and Elswyer is back to its chaotic state. Black Marsh went back to being independent, since they saw the Empire as nothing more than a weak, useless power, and so on.

Though, I wonder what's up in the human held lands. We didn't hear much about them.

Basically, you had one being holding off all other races from killing each other, and establishing order instead of anarchy. But now that central figure has been removed, everyone is back to trying to rip each others throats.

I would think that either the human lands have banded together, or (more likely) seceded from the empire and possibly relapsed back into how they were in Daggerfall. Skyrim is/isn't a part of the empire (Agents say that they despise the duty of spying in Skyrim.) Hell, even Cyrodiil split after Oblivion, and Titus had to reconquer central/western Cyrodiil to start the empire back up again.

It will be interesting to hear what became of Hammerfell and Orsinium, among other places that aren't mentioned in "The Infernal City". Hopefully the second novel will fill in more of the blanks.

The orcs were loyal servants of the empire, and apparently had good relations with the bretons after TESII. Of what's going on with the redguards could be a bit of an issue. But, if Titus or Attrebus are powerful enough, they could bring back the human provinces back with little problems.

Half of them... ish. They were allied with Wayrest and Wayrest doesn't like Daggerfall much.

While were on the subject of the book, i've been wondering: does it mention anything of what became of the CoC?

nope, other than "...the gate at Kvatch was closed..." if that counts.

he was a Blade. Blades don't get famous, only the Emperors they serve do.

Well, Sul and Attrebus briefly visit the Shivering Isles... so yeah. The CoC is the Prince of that realm, being Sheogorath and all.

He makes pretty flowers smell like skunks.

Did Morrowind really get conquered by a bunch of Argonians? Black Marsh hadn't been able to prevent slave raiders attacking their settlements for centuries, how on earth did they suddenly muster the ability to conquer one of the most cloistered nations in Tamriel?

Well, Morrowind really wasn't in much of a state to fight back.

What happens there? I haven't had the opportunity to get the novel.

Because the Hist told them to. The Argonians, when united by the Hist, are obviously a force to be reckoned with. The Dunmer couldn't conceive of this, and paid the price.

It probably didn't help that their land had been visited by catatrsophe in the form of the Ministry, either.

The short version is that the Ministry of Truth dropped outta the sky and destroyed a massive portion of Vvardenfell/Morrowind. The MoT also created seismic activity which woke Red Mountain up, so now most of whatever wasn't decimated by the MoT is now volcanic wasteland. A massive amount of the population of MW obviously perished in this event, and much of the survivors fled to Solstheim. The Argonians didn't have much of an issue with these things in mind...

Quite. This also happened during Oblivion, when the Argonians were "called back" to Black Marsh to close the Oblivion gates - this obviously couldn't fully be expressed in game due to many Argonian NPCs crucial for quests, but we're to assume nearly all of them went into battle mode and fled into the heart of Argonia, where they dealt Dagon's forces massive losses.

Ass-kicking lizards. The only way to improve that is to throw in some drills.

I'm sure they used spears and crossbows liberally.

and traps.

That's why you don't see any on Cyrodiil. The Argonians were stockpiling them.

You know what? I think the the book is false and the play, "Sheogorath and Champion of Cyrodiil" will be the next in line, why is everybody relying on the book? Bethesda did not confirm it was true or not.

Bethesda has already said the book is to be considered canon.

There is an "Official" thread for discussing the book http://www.gamesas.com/bgsforums/index.php?showtopic=1061320