I juust mounted a VX2 on a customers rifle this afternoon. Personally, I like the Vortex line but thats personal preference. Far as Leupold being made here, not sure. They are very cagey about orign of products.
Far as warranty, the industry standared is a lifetime no questions asked returnable guarantee, driven by customer demand more than anything.
Optics manufacturers have to 'step up' or get passed up.
You really can't go wrong today no matter what yoiu get unless it's really cheap (like Tasco).