Well FFX and FFVII take place on different planets (with X taking place on Spira and VII taking place on Gaia), and considering that Tidus probably never left Spira, I don't think there's really any connection there.
I'm getting X-2, and am thinking about getting X. My dislike of Tidus has lessened over the years, largely thanks to Duodecim, and since it's the international version, I'm willing to give it a go. Though, honestly, I wish SE would go back and make modern remakes of the original games. Given the cinematic for FFIV DS (which looks fantastic and, if you've never seen it, I recommend giving it a watch), they certainly have the mindset for it. It seems that they've resigned themselves to the idea that the pre-3D games should be simplistic and mostly the same, spanning mobile consoles. There's so much potential in innovative remakes, though. It's sad, really, because you don't see grand remakes like you used to.