Lets assume the email is not fake. No, they are warning you that if you spend more you will be hit with fees. To most people $24 would be dangerous with checks out in the mail and such.
You don't have to. The balance notifications from B of A are just what they say they are, a courtesy.
And btw, they are real (at least the ones I've received).
I wouldn't trust any email because so many scams and phishing. Log onto your account (without clicking any links in email) and see.
The late fees that you will be charged will send you into shock.
The initial fee plus daily fees.