Businesses that are eligible for you to earn rewards are shown in the app with the % of rewards clearly marked on their profile. You can see a full list and map in the Discovery tab with the "Can Earn Rewards" filter

Yes! To connect additional cards, you can navigate to your Profile -> Linked Accounts and Cards -> + Link Card.

If you have different cards under different people (eg. your spouse, another authorized user, etc) but the cards link to the same bank account, it should only be added by 1 user to prevent duplicate transactions. If we detect duplicate cards, it will be deleted.