A unit's trait matters so much in ASTD X because a Poor trait applies a real -15% damage penalty, while a strong, rerolled trait pushes that same unit well above its base performance.

No, you generally can't still get Limited units after their banner ends through normal summoning, which is exactly why they carry extra value on accounts or listings that already have them.

The difference between Gems and Summon Tickets is that Gems are the core currency spent directly on summons, while Summon Tickets are an alternative way to pull units, sometimes with a guaranteed rarity, earned through quests and events.

Yes, you keep the units, Gems, and materials included with my purchase, exactly as shown in the listing.