You can use the ps2 guide for getting through the gameplay, certain story sequences have changed from the original as well as a new area or two that won't be in the ps2 version guides.

Yes, you can use the guides for the PS2 verison of Tales of the Abyss. There some changes like the controls that are different.

You can use the strategy guides from the PS2 version. However, keep in mind that some sidequest cut-offs and starting points have altered slightly. Other than that, there shouldnt be any differences in the strategy guide.

NO. I tried using the guides and the directions they gave you were crap. I got lost several times trying to follow those things on the 3ds version. Plus the guides that they do have don't have one that just does the main quest. They confuse you by sidetracking and making you do all these different sidequests and stuff. They won't come out and just say "you gotta go here_______."