First I'll start with a small correction:
The 6th age was just released and I can´t give much information game wise. (The campaign setting will contain them, but it will also allow you to play in other ages then in the 6th).
There is no 6th age. There.
There have been 5 ages in Dragonlance:
Age of Starbirth (First Age)
-the gods create Krynn, wage wars and create the first races:
gods of good create metallic dragons and elves,
gods of neutrality create humans and
gods of evil create chromatic dragons and ogres
-these races than proceed to wage wars
Age of Dreams (Second Age)
-the graygem creates additional races
-all of the world is slowly populated
-the second age ends in Huma's war and all dragons are forced to
leave the world
Age of Might (Third Age)
-the empire of Istar becomes the most powerful nation and begins
exterminating 'evil' races, the last kingpriest of Istar demands
from the gods the power to eradicate evil resulting in the gods
casting a fiery mountain on Krynn that devastates the land,
this is called the First Cataclysm
Age of Despair (Fourth Age)
-the first half of the fourth age the gods were believed to have
abandoned Krynn (which wasn't true), and there were no clerics
or dragons around
-during the second half the dragons come back and people reach
out to the gods once more resulting in the return of clerical magic
-war of the lance comes and goes, Raistlin tries to become a god
and fails
-the chaos war devastates the land and the gods truly leave at
it's end, this devastation is called the Second Cataclysm
Age of Mortals (Fifth Age)
-at the beginning of the fifth age the only magic is mysticism
because of the absence of the gods
-powerful dragon overlords (who are epic size dragons) arrive to
Krynn and attempt to become it's ultimate rulers
-the war of souls happens, some of the overlords are killed, the
gods return and now there are 4 different types of magic around:
focused divine (clerical), ambient divine (mysticism), focused
arcane (high sorcery, wizards), ambient arcane (wild sorcery, sorcerers)
A couple of points on Dragonlance in general:
-It's basic filosophy is balance, good neutral and evil need to be
kept equal and everyone has to have a choice between them
-There are 21 gods on Krynn, 7 good, 7 neutral, 7 evil. Plus 2
higher gods, Chaos and the High God. Clerics are faithfull
followers of their gods and usually choose a single deity to
worship. None of the DL deities have racial preferences as to
who they accept as their followers.
-The most prominent races (other than dragons) have been ogres,
bakali, elves, humans, dwarves, gnomes, minotaurs, kender and
draconians.
-There are three moons on Krynn, the white, the red and the
black. The moons represent the gods of magic. All wizards must
pass a test and join the Conclave of the Wizards of High Sorcery.
White robe mages follow the path of good, red neutral and black
evil.
-There are three lawful Knighthoods on Krynn. The Knights of
Solamnia follow the path of good, the Knights of Neraka/Takhisis
follow evil and the Legion of Steel promotes balance.
-There are 14 types of dragon, 7 good metallic and 7 evil chromatic.
And no they are not smaller than in other settings.
-There are no drow, sahuagin, lycanthropes, orcs, gem dragons
or halflings on Krynn.
-Magic is just as potent as in FR, just more hidden and not as
easy to come by (which makes it relatively more powerful).