I don't think there's enough to say that Taban & Lara are dead. I personally don't really believe they are. For all we know there's another house on Ashtear Island just for them that we never see and they left the old house for Lucca to convert into the orphanage. The reason they have nothing to do with Kid after the attack is probably due to the fact that Kid struck out on her own looking for revenge...they probably don't know she's alive...she probably didn't want to have to deal with them either trying to convince her to stay with them or else just the fact that they'd talk about Lucca...
As for the receipt (hello completely new topic [that's been discussed before]!)...It's INCREDIBLY ambiguous. There's nothing convincing that states who's receiving what. The Porre Navy is stated as being one of the only ones capable of transport from El Nido to the mainland, so it's entirely possible that Lucca transported or had something transported to there through them (perhaps, as mentioned before, to her former colleague Luccia). And a random jumble of letters & numbers certainly doesn't immediately bring to my mind WEAPON...Makes the most sense that it would be something for Grobyc now that I think about all of the connections...
