The difference between a card's rarity and its Border is that Border, Basic, Gold, Rainbow, or Secret, applies to any card and multiplies its base stats significantly at each tier, while a card's underlying rarity determines how hard it is to roll in the first place.

Yes, you can still get Event Cards after their event ends, but only if you obtained at least one copy before the event concluded, which unlocks it for normal rolling afterward.

Yes, Traits carry over to every version of a card, since rerolling a Trait applies it across all Border variations, Basic, Gold, Rainbow, and Secret, of that same card.

Yes, you keep the Cards, Traits, and Accessories included with my purchase, exactly as shown in the listing.