The difference between a Limited and a Limited U item is that Limited U items are individually serial-numbered from release, while regular Limiteds are simply capped in total supply without that per-copy numbering.

You need Roblox Premium to trade or resell a Limited because Roblox restricts those actions to Premium subscribers, though buying a Limited outright doesn't require a subscription.

Not exactly, since RAP is a rolling average of recent sale prices rather than a fixed value, actual trades can land above or below it depending on current demand and available copies.

Yes, you keep the Limited item exactly as described after purchase, including its copy number if it's a Limited U item.