Tidus' Disputed Existence (Possible Spoliers)

[Renmiri]

It might help if you think of Dream Zanarkand as a giant Aeon, the product of the collective unconscious of counless Fayth entombed on Mt. Gagagzet. Like any Aeon, DZ exists in a solid state of being as long as the Summoner continues to summon (which Yu-Yevon has been doing for 1000 years).

Unlike a regular summonable Fayth, where a single corresponing Aeon appears, the makeup of DZ has shifted and evolved over the millenium as people are born and die. So each individual in DZ is an expression of the collective dreams of the Fayth, rather than their individual dreams.

There's nothing to suggest Tidus has Shuyin's soul, although no doubt many Fayth knew Shuyin personally and his appearance was the model for Tidus. However, there's nothing to suggest that it was a deliberate act on the part of the Fayth.

I think Tidus existed even after the Fayth woke up, just in a non-coporeal state.

Good guesses, all of them. This is exactly what Square Enix book on FFX and X2 - Ultimania Omega, Battle and Scenario say

Look for pmog's translations at GameFAQ or for Ryu Kaze's translations at IGN and Wikipedia. Ryu just finished (july) some about Shuyin that refer to just that.

Also, DZ is indeed located in an island - see proof below - so Jecht, Tidus and Auron used Sin to get in and out

Since Spira was at it's technological peak 1000 years ago this is not suprising. However, the rest of Spira reverted to a less technological state while DZ maintained the pre-Sin technology levels.

That is the only nit I have. Ultimania books put the peak of technology at 3,000 years ago. Ultimania doesn't tell us what happened between 3,000 BG (before game) and 1,000 BG to make it decline. We do know what happened to make Spira so empty and devoid of technolgy on FFX: Sin and Yevon's Church both made sure that all big cities and big machina were obliterated. At Wikipedia we even have that Yu Yevon made Sin search for technology to destroy, as he imagined that Bevelle would be the main danger to his Dream Zanarkand plan. Do check the FFX and X2 pages at Wikipedia. Both of them were among the very few game pages selected as "Featured Article", i.e. "the best in Wiki". The FFX page was even front paged on July 19, 2006, the 5th anniversary of FFX's release
http://en.wikipedia.org/wiki/Final_Fantasy_X