I just stumbled upon this thread - too bad I didn't see it earlier! I see that Riellyscions still visits here, so maybe he'll stop by...
What is the story behind the word trust being spelt with a V ?
Just a common stylistic device used by many artists of the time, though it dates to a much earlier time (Think Romans). It is rooted in the fact that the Latin alphabet did not have distinct/separate letters for the current "U" and "V."
You don't see classic commemoratives in the original packaging at all these days.
I don't believe the packaging shown is original packaging of the Texas Centennial Committee. It appears to be something put together by a coin dealer. For most collectors, such packaging would add very little value to the coin. Verifiable original packaging from the Committee, however, would add a real premium!
What is the golden color ?
The color you see appears to be a combination of toning and chemical transfer from its package. As you've stated that the coin has strong sentimental value, I would suggest having the coin conserved by a professional coin conservation service and then graded/encapsulated. This would stop further corrosion, maximize its visual appeal and protect it going forward.
Please post any other questions you may have.