Couple of Questions and potential spoilers:

[Zora]

Anyways, could someone explain where I could find the Mighty Guard Spell. My Guide Book says "Lake Near Carwen," though that doesn't explain much. Exactly where do I go to fight him?

Also, what section in the Interdemensional Rift does "White Flame appear in?" (Void, Cave, Castle, Forest, or Desert?)

And was a good place for EXP training?

[Zeromus_X]

Well, I don't know what the guide is talking about. I guess mistakes happen. To get Mighty Guard, you have to sail around in the water near the sunken Walse Tower. It's a rather rare encounter, and it could take quite awhile or not very long at all to encounter the Stingray enemy depending on your luck. But I'd say it's worth it, as Mighty Guard is an invaluable Blue Magic (also note you have to Control the Stingray to get Mighty Guard. Equip a Hypnocrown to your character with the Control ability, learned from Beastmaster).

I'm not sure regarding your second question.

Now, as for experience, you could always hang out in the areas before the crystal area of the final dungeon. Iron Giants are pretty good for Exp, but don't appear frequently, and aren't an efficient source of exp gain. Of course, besides the final dungeon, the bonus dungeon easily gives the most experience, though you have to beat the game first.

[Zora]

White Flame is an enemy that gives you the Blue Magic spell whitewind... according to my guidebook which proved to be VERY accurate :rolleyes2

[,,,]

I found the stingray in a tiny lake near a town, it was only the second encounter I faced. I don't know if I was very lucky or if it's less rare in that area. Might want to try it if you get frustrated with the other location.

[Jowy]

White Flames appear in the forest area, where you fight Calofisteri.