Oh, and I keep meaning to write this in response to your request for Ys III info:
III is the bastard child for a reason. While I still like it, I think that's mostly because of its awesome soundtrack, and because it's my first Ys game. Comparisons with Zelda II are warranted: the game is hard as hell, and for much of the same reasons, i.e. strong enemies and very limited attack range. You only ever get the sword though, and the one ring that could be useful on the masochistic boss fights (the time ring) doesn't do jack against bosses. And the bosses tend to be something else. Going from full health to death in roughly a second is not uncommon. Strangely, the early game tends to be the hardest, so if you can ride that part out you should be okay for the rest of the game.
The levels are not linear; there's a fair amount of branching in all but the final level. Indeed, you have to revisit a portion of the first level later in the game, after you unlock a portion that you couldn't get far into before. That said, the exploration is pretty limited. The branches tend to be fairly short (although there's invariably loot at the end), and the ones that are lengthier stop you a short ways in until you do something to unlock the later portion.
What I suggest is skipping Ys III and ordering the remake (Oath in Felghana) from Falcom or eBay, and then applying the translation patch. Falcom's actually the better choice. They love their overseas fans, and they often give us extra goodies for ordering directly from them. I'm talking full official OSTs and bits of official artwork here, which for this series is a nice bonus indeed!
At the very least, make sure you find a way to listen to Felghana's soundtrack. It's possibly my favorite video game soundtrack ever.
Oh, and play Little King's Story! :-P