"what is the significance of the 1996 (Opening date of Texas Station)"
It was called Texas prior to 96. Stations took it over.

"and the unusual LE numbers, 7400 & 5100? Find out!"

They mailed out postcards to come in and pick a chip from a box. Looks like they mailed 12,507 postcards. Total budget for giveaway $54,700.
This is a good promotion, they have done it several times. Good exposure for the hobby.
The card said, "Cash it", "Collect It", or "Play it"
There was about 1,000 people in line at 10AM this morning.