"Under then nrst, business inputs are not taxed. Hence products sold outside the US will no longer have the costs of our tax system built into the price... allowing our US companies to compete on a more level playing field."
Major problems here. First, define 'business inputs'. You've just opened the regulatory tax version of Pandora's box. Pages and pages of words designed to define 'business inputs'. Indeed, much of today's tax code is designed to do just that. You've just taken a big step back to where you were with today's code.
Also, item will be diverted from those scheduled for export. You'll wind up with having to have a tax stamp on every item to prove the NRST was paid on that item. Think of the stamps on cigarettes and booze.
What business buys to produce a product.
The tax is only on new goods (never before taxed) and services.
If it's sold in the US for retail consumption and it's never been taxed, the tax is due. The tax is collected at purchase. I don't know how items could be "diverted". Nevertheless, cheating is going to be a problem in any tax system. The intent is to minimize criminal activity. You're never gonna eliminate it. If the tax is fair, easy to understand, and it's easy to get caught with significant penalty then cheating would be lessened IMO.
I think in some respects you have the cart before the horse. Certainly spending is a horrible problem, but the FairTax is a tax bill, not a spending bill (nor can it be). To repeal the 16th, there must be an practical tax bill in operation else you'd be exp[ecting the Congresscats to eliminate the taxes on income with no replacement - very few in Congress are THAT foolish (and if so, they deserve to be ousted).
So trying to get rid of the 16th first cannot possibly happen while once the FairTax is operating as a revenue neutral tax bill, the 16th becomes an anachronism much like the Prohibition amendment and serves no useful purpose. It certainly would be repealed in short order ... especially once citizens tasted the benefits of the FairTax.
Also, I think you missed the point that the FairTax REDUCES the costs of exports - no tax stamps required since the exports are not taxed.