ALL of the proposed constructions are reasonable and potentially interchangeable in common usage. They would be more, or less, understandable from the audience's point of view, depending on the audience. You might find some variation of the suggested usages regionally (colloquial). Some of the constructions listed leave modest room for different interpretations, and thus, potential misunderstandings.
-"The bank is open at 7 am and closed 4 pm"
does not specify that the bank closes at the hour of 4 PM. It grammatically specifies that the bank was closed by that time on some ungiven past day. The bank could be closing at 3:30. We don't know. It could have been closed some previous day at 4 PM, as closed is past tense. We don't know. However, in common usage, most listeners would assume that the speaker was referring to the same day, with the intended meaning of "will be closing at". This is because we have a common experience. We all know approximately what time the bank closes, and we expect the speaker to be consistent inside a sentence. For the speaker to jump from today ("open at 7") to yesterday ("closed 4") would be inconsistent.
A speaker concerned with clarity would more likely use the more specific construction, e.g. "closes at", or "is closed at". Also, while "it's closed at" is common usage, one could say that it is more correct to use "it will be closed at" (although this might also be pedantic).