A very useful post!
The most useful feature would be the reminder of card rentals that will be expiring with 24 hours. Sometimes it's so easy to forget when I am too focused playing the game.
One suggestion I have is, under the Bulk view, to allow users to customise the columns that they want to see. For example, I might not need or want to see "yROA-B %" or "Market Rent" if I am constantly renewing the same cards. If I could filter these columns out, it would be less cluttered (especially when I am viewing from my mobile device).