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I would recommend not answering unrecognized numbers both as a general rule, and especially right now as you are going through this period of your BK before the automatic stay kicks in. Your phone may blow up for a little while, but I promise you will feel relief when it quiets down. If you have a way to add numbers to blocked list (without paying your carrier) or sending them to voicemail automatically, make liberal use of it.
As far as the late notice, just set it to the side and try not to worry about it. You can provide it to your attorney if you wish, but it's not their biggest concern right now. If you get a collection notice (would come from a separate agency), definitely present that to your attorney right away as that will change your BK filing.