User blog comment:IamJakuhoRaikoben/Chapter 245: The Unbranded Man, Review./@comment-3987368-20110730184547/@comment-4078901-20110730194248

Natsu can eat fire without suffering any bad effects which means he can eat Totomaru's and Bora's. Although he refuse to eat Totomaru's Orange fire since it was stinky. Eating other elements gives Natsu a power boost but causes him to be sick after a short while.

Also, I think Lucy joined the guild in June, as seen at the end of Chapter 3 (I think). And the current arc is taking place in the end of that year or the beginning of the next.