Are there going to be any region restrictions?
There are region restrictions only at the point of sale, but after that there will be no restrictions, so you can effectively play on any world server you want.
Are Beta Weekends Events as part of pre-purchase bound by NDA?
Nope. You can discuss freely about the game if you're in beta.
Do any of the digital items offer advantage, such as the Hero's Band?
To address each one individually:
Misfire Wolf — like racial skills, this too is a flavor skill, and is weaker than any profession elite skill
Hero's Band — gives a boost in early levels, but is far superceded with other in-game items.
Chalice of Glory, Tome of Influence & Golem Banker — time convenience items with a limited use.
In short, none of the items don't offer any advantage over those available in the game.