Once a bankruptcy notification has been received by a creditor (specifically, a financial institution), must ALL communication be routed through a debtor's attorney, including correspondence which would NOT be "an attempt to collect a debt" (e.g. overdraft notices, statements, etc.)?

The protection of the stay is an umbrella of protection against collection of the debt. While I am not an attorney, I think you could, but it would strictly have to not be any inference of collection. That said, you're likely to be more successful if this pertains to your loan, if it goes through their attorney.