Florida Rules of Criminal Procedure 3.132(c)(1) provides, in relevant part:
A final order of pretrial detention shall be entered only after a hearing in the court of trial jurisdiction...No testimony by the defendant shall be admissible to prove the guilt of the defendant at any other judicial proceeding, but may be admitted in an action for perjury based upon the defendant's statements made at the pretrial detention hearing, or for impeachment.
So the testimony from the bond hearing is admissible only to impeach - it can be offered only for certain permissible purposes, such as pointing out a prior inconsistent statement (if he contradicts his testimony from the hearing). There are several other purposes for impeachment, but that's the most likely one to come into play, at least when it comes to his testimony at the bond hearing.
As for testimony at the self-defense pre-trial hearing (if he demands the hearing and testifies), I'm not sure about the admissibility. But I would imagine that if he also testifies at trial, it would also be admissible only for impeachment.