Gives a good boost of attack if you have multiple monsters in your graveyard. Your other plant type monsters won't get destroyed if you have Talaya on your side of the field, but this will not prevent talaya herself from getting destroyed.
Would I ever need 2 or 3 of her in 1 deck? I'm getting dust knight and got him but not talaya yet and am debating if I should get her before I reset or just reset so I can start working towards Dust Knight again and get her next time.
Not really. Plants aren't that strong right now, and this cards effect pretty much make fragrance storm useless, while the sunflower princess synergizes with it. That being said multiple copies will let you pull off the old screech plant food chain storm resurrection combo