Each time you cast a spell, she creates more tokens you can sacrifice to the Elder Dragons casualty ability so you can copy your instants and sorceries
Sell valuable or in-demand cards individually, and use lots only for low-value commons
You can obtain the Cyndaquil (1-Diamond rarity) card by opening Wisdom of Sea and Sky: Lugia from Wisdom of Sea and Sky set
Trelasarra is best in formats where you can run a playset, in my opinion, and only half-decent in Commander
This is important for insurance purposes in case anything happens during transit
Unlike the cards in the main set, Through the Ages cards do not become legal in Magic's Standard format (though they still are if the existing card was already legal there, of course), essentially just making them alternate art versions of those cards