An antoynm is someting that is the opposite of another thing, for example wet is an antoynm for dry. so no you can't use it with that phrase.
Back into the fight. Could also mean back into the struggle of life.
Back
Yes. The note has a blank back side.
synonyms: iterate, recap antonym: take back
It's possible that you have an error coin, or more likely that the back could have worn off from use.
To "Pull Back"
back dancer
pay back
back-arm
look back
An antonym for astride are: astraddle athwart on the back of piggyback sitting on straddling
Nape is the back of the neck.