Better yet, tell them that if they have questions, to submit them in writing to your attorney and that HE will get back to them. NO direct communication to the FBI, only letters from your attorney, mostly saying "my client tells me that, to the best of his recollection, X happened" or "my client does not recall". You can face perjury for lying to the FBI, but I'm not sure (I'm not a lawyer) whether a statement from your lawyer that he heard you say X, is similarly actionable.
YES. That would be hearsay.
Just like when the judge rules against your request to have another cop who was present and heard everything (i.e. the cop in questions partner), say anything that will defend you in any way.