1: No study is needed on this, since the label is not asking "is this a good modification."  You're required to notify if your product is modified.  It could have been genetically modified to have extra Vitamin A or to release the T-virus... either way... are you really saying companies don't know the breed of their own corn crops?  Plus, one more thing on this which is at the bottom of this post.
2: Okay.  No argument here.
3: This isn't that hard.  Cigarettes and allergy-inducing ingredients have given plenty of experience in disclosing "may contain genetically modified ingredients."  Additionally, as with cigarettes, the regulatory agency often writes what is legally required to put on the box (that Surgeon General's Warning is not the wording of the cigarette companies).  In fact, I just went on the FDA website and they already have a series of pre-written "how to disclose GM foods" setups.  So yeah, you may need a lawyer... but you could probably get away with hiring dpenguins! 
4: Have you seen labels nowadays?  Seriously, this same argument could be applied to sooooo many foods that have labels today.  This isn't actually a unique problem.  If it were, we would never know about the high fructose corn syrup, red 13, etc., in our food.  This isn't a game-breaker for businesses.
5: This is easy to fix, and at every level.  Why?  Because businesses have business relationships.
Example: I purchase wheat and corn to make corn bread which I package and sell.  Generally, I ask my suppliers basic questions about their products (after all... I can't exactly use white corn for corn bread... who would want that?  bleh!).
Now, the suppliers are the ones actually handling the product they sell.  The farmer has complete control over their crop, supplying the seeds used to grow the corn.  More than anyone, the corn farmer knows what type of corn they're actually growing, because they  have complete control.
So... back to my bakery!  How do I find out what my bread is made from?  Simple: call my wheat and corn suppliers.  "Hey, are you using genetically modified corn?  Yes?  Okay, thanks!"

It's not like they're buying their business supplies out of the back of someone's Ford.  There's formal business contracts which generally include such disclosures.  This means the actual cost of determining whether or not food food is genetically modified... is near 0, simply because the supply chain can provide that exact information.

Okay, seriously... Polaris?

http://files-cdn.formspring.me/photos/20120607/n4fd113fd674c2.jpg

(No, this is not part of the "Guess who or what" game!  This is Genesis right now)

Warned, Gen.

It's a gun!

I'm going to give you one shot to prove to me that wasn't a drunk post.... then I'm editing it as off-topic. 

http://i2.kym-cdn.com/entries/icons/original/000/000/015/orly.jpg

http://en.wikipedia.org/wiki/United_Nations_Security_Council_Resolution_478

But yeah, that then brings an entirely different question into the field: If US policy toward Israel was an issue strong enough to manifest as a key issue for the Jewish population... the Jewish population should have been Republican for decades. 

It has to do with Romney in that "votes" are part of a competitive event (an election) in which votes lost by one candidate either abstain or generally vote for the other candidate.  In effect, this thread is framed as an issue within the issue of election result prediction.

Functionally, it's the equivalent of if a candidate made an accidental racial slur against a minority, and someone claimed that the slur ruined that person's chances at winning.  Saying "but his opponent is actively attacking that minority to the point where they would never vote for him even if they did turn against their favored candidate" is still an on-point reply.

EDIT: I'm only interjecting with regards to the question of whether a Romney-related equivalent issue is on point.  I haven't actually read the link enough to give a warranted ruling just yet. 

Psst... notice Gen's tag. 

Why... do people take me seriously on this forum anymore?  Jeeez!