User blog comment:IamJakuhoRaikoben/Chapter 327: My Part Too, Review./@comment-5113042-20130413152152/@comment-7418318-20130413160017

How would Igneel have sent Natsu through time?

The eclipse gate only opened a tunnel between the year X791 and the distant past, so that's not an option for sending him into X777.

As for Sting and Rogue being taught by Dragons, on the last two pages of chapter 293 Igneel said "Weisslogia, Skiadrum. The Dragon Slayers that you've created. Let's see what they're made of".