Does counting good deeds done for someone constitute a "favor" (minnah)? And does describing this act as "self-defense" make it so? And is it considered disbelief (kufr)? And does a person become a disbeliever if they utter a word that outwardly appears to be disbelief without intending it, and does repentance and the declaration of faith (shahada) thereafter remove the disbelief, or must people be informed of a change in meaning?

It appears the questioner is suffering from whispers of disbelief (waswasat al-kufr). The treatment for this is to completely disregard these whispers, to cease engaging with them, and to refrain from asking about them, while supplicating to Allah for healing. Listing good deeds when one is denied or mistreated is not among the forbidden forms of "mann" (boasting of favors). It is permissible for a person to enumerate their good deeds if they are denied or mistreated, based on the Almighty's saying: "Do not invalidate your charities with reminders of your generosity or injury" (Quran 2:264), and the Prophet's (peace be upon him) saying: "Three types of people Allah will not speak to on the Day of Resurrection... the one who reminds people of what he has given" (Sahih Muslim). However, this applies to someone who reminds others of what they have given initially [without provocation]. The Prophet (peace be upon him) indeed enumerated his good deeds to the Ansar when they desired the spoils that others had received. As for uttering words without intending a meaning that constitutes disbelief, it is not disbelief. All that is mentioned in the question are mere assumptions stemming from whispers of disbelief.