Does each card have it's own balance and spending limit?
No. All of your cards are linked to a single Liquid Account. This means they share the same available balance and spending limit.
Because the cards are tied to the same account:
Shared Funds: A transaction made on one card will immediately reflect on the total balance available to your other cards.
Account Settings: Any changes made to your Liquid Account (such as withdrawing funds, changing spending modes or updating limits) will automatically apply to all related cards.