... Why did Lilties suddenly go from being tiny-but-powerful warriors in the original Crystal Chronicles and My Life as a King, to weak Alchemists in Ring of Fates, then back to tiny warriors in Echoes of Time? You can't even say that Meeth was just a divergence from the Lilty stereotype, as it also applies to multiplayer, and seemingly to NPCs — the magic shop owner is a Lilty, too.
If I'm remembering things correctly, Ring of Fates takes place before the other three. It probably takes place before the Liltian world conquest as well.
Those changes are nothing compared to their change in Crystal Bearers. Apparently, the Lilties went though a huge evolution in the 1,000 year gap between games. Now, very few retain the short and stout look from the original. Many of the guards look more like giant ogres! Also, the eldery Lilties look eerily like Oogie Boogie from The Nightmare Before Christmas!
The most common explination for that one is that there have been so many Lilty/Clavet marriages, that much of the lilty race are hybrids.
For that matter, does it even take place in the same world? There's some things that seem to indicate that, but some stuff is just weird if that's the case.
The inclusion of the same races over the course of each game are an indicator that it's the same world.
Well, Ring of Fates and Crystal Chronicles are definitely in the same world (as evidenced by the Rebena Te Ra dungeon and the Lich's presence) and it is stated repeatedly in My Life as a King/My Life as a Darklord that those take place in the same world as well.
And since characters from the My life as a King, specifically, Leo and Chime are in The Crystal Bearers, we can assume that that takes place in the same universe.
One of the games notes parallel dimensions exist, and then makes a vague reference to another game. The implication is pretty clear, but it just seems the series is pretty half assed about timelines and such.
Exactly how long do you have to play the first game before a plot begins to amass? Is there even a plot, or am I just traveling the world looking for shiny water?
Since the plot is mainly explained through Random Encounters on the road, there's no way to tell how long to wait, though usually it's a while (and it doesn't help that there's quite a few subplots that are explained erratically or just plain hard to activate the cutscenes for). Really, the first dungeon crawl that directly links to the plot is the second time going through Veo Lu Sluice to refill the river so you can get to Leuda.
You can complete the game in at least five in-game years (any time you replay a stage you have collected myrrh from for grinding does not count towards your yearly timer, this helps a bit if you can't get anyone else to play with you), but by that point, you should have pieced together all of Gurdy's encounters (his passages are clues of what you need to do in Leuda Desert in order to get the unknown element and get to Mount Vellenge) and witnessed some of the Black Knight encounters.