Have several questions

[Tolg]

Spoiler Alert, click show to read: 

The first Persian Empire was that of Cyrus the Great, the Achaemenid. With the fall of
Darius III Codomannus, the Achaemenid Empire was no more.
The second Persian Empire was that of Arsaces I, and it was known as the Arsacid Empire,
or the Parthian Empire. These Parthians, who were once nomads, carved out an empire that
lasted twice as long as the Achaemenid Empire.
But the Arsacid kings were not inheritors of the Achaemenids by blood, but by tradition. The history of the
Achaemenid Empire had been lost and was replaced with myth and tradition - the relief at Bisutun was already
being wrongly attributed to the legendary Queen Semiramis by the 4th century BC.
There were, however, survivors of the old dynasty of the Achaemenids , who could claim
lineage to Cyrus, Darius and Artaxerxes - and, more importantly, who had the power to do
so.
The Orontid dynasty (Yervanduni) of Hayasdan were one such family. Descended from
Orontes I (Yervand), satrap of the 13th satrapy, and then later the 10th as well, in the 4th
century BC. Orontes I was reportedly of royal Bactrian blood, but had also been wed to the
daughter of Artaxerxes II, Rhodogune.
Orontes' power and respect at the Persian Court was enough to have himself pardoned of treason when he led a
satrapal revolt against the Persian King.
In 272 BC, the kingdom of Hayasdan, still beneath the rule of the Orontid dynasty, was not
the homogeneous kingdom that would later mark its rise to power in the Caucasus. Whilst
able to withstand the political pressure of Arche Seleukeia from within her mountain
fortress, the disparate tribes of Hayasdan could not pose any threat beyond the confines of
that self-same fortress.
But, perhaps, had these peoples of Hayasdan been united sooner, beneath one king, the star
of that kingdom in the Caucasus would have risen before the Parthians could fall upon the
Hellenic Empire and claim Persia for themselves. And with the might of the Caucasus
behind them, perhaps just perhaps, the second Persian Empire might not have been called Arsacid - but
Orontid!

Taken from the Guide to the Hayasdan reforms on the EB homepage.

And as mentioned before, the Seleucids own most of Persia at the start of the game. They are however not a Persian faction but a Hellenistic faction with a lot of Persian units.

[Cute Wolf]

Yes, Kardhastim can bribe spartans... look in EDU file...

The 3 spartans in the Kardhastim service maybe Xantthiphos's friends, or maybe the Kardhastim bribe them? The H campaign ai seems very fond of bribing my armies, why they didn't bribe the spartans as well?