The individual cards for this deck would come out to over $60 to put together yourself, so yes, all of these decks are a good deal packaged this way
If you don't have fire energy attached to your Mew, you don't have to discard anything
In a multiplayer setting, though, you can choose who gets the extra copy, allowing for some interesting political plays and serious gameplay swings
Due to this unique quirk, MTGs Lead Designer, Mark Rosewater, explained that [Structures] were sort of like attackable enchantments. Despite seeming like an incredibly engaging mechanic, ultimately, it wasnt meant to be for Structures
I recommend building an Excel file to get your organized so that you can clearly understand what your cards to and where they fall