2) The king assassinated in Arid's story is the same, that happened about a decade or so ago.
2nd age history excerpt:
Humans were spawned from the tass of the planet through the melding of the hands of Latrinian High Councillor Archtus underneath the direct influence of Ixazu's dream control. The divine influence of Ixazu had however overestimated the stamina of the Latrinian God who died before the process was completed, leaving the race to develop prematurely without the innate power of the Latrinians and the subservience to Ixazu. Born of powerful aspects of dream, earth, and Gaia, humans are both blessed and cursed with all the best and worst characteristics of all three. Although now born onto the planet, without the leadership of the controlled Councillor Archtus humans would have no real guidance and were free to evolve in many various fashions until such a time that the elder gods might arrive. Ixzazu would do his best to instill a racial fear of Dwarf and Latrinian through their dreams so as to discourage influence from them.
That is the origin of the human race, however Elves and dwarves evolved into civilizations long before humans did. The first humans did more resemble hominid man, and thus were treated more like animals than civilized beings to the elves, though by the time the floating cities were forged by the gods in the third age, the humans had attained more of barbarian-like cultural status, but by that point the elves and dwarves were flying with the gods in magical cities, so the humans still didn't seem relevant until the instance of "the first", a reference to the first magus. The details of that are forgotten legend, but there are historians that see similar elements of the tale of Ishmial and assume they may have been the same person, have had something to do with each other, or are both loose fictions that may have influenced each other.
After that humans weren't kept as slaves but were allowed to roam the lands and even settle in places not to close to elven and dwarven borders or over resources they wanted. More or less they were second class citizens by the time Magus Vaorren rolled around, and being that he became a potent force and hero of legend (prior to his betrayal) humans gained a few points in their favor as a race, until he betrayed everyone and annihilated most of the orc, drake, elf and dwarf civilizations. After that, those societies (and the races as a whole) were decimated (and are still in recovery today). Since the Vaorren nobility kept humans as favored, easily controlled cattle and the fact that they breed fast and adapt well, they repopulated a lot of the dwarven and elven lands.
The only other thing bearing mention here about previous human cultures is the Necrolytes, which rose to power on the other continent, which was a human-based race and was treated as a threat and was driven to near extinction and is kept in check today by the surrounding warring factions.