How many times before grace is imparted? What about when it is not accessible?
What about taking ALL OF SCRIPTURE, what would it say? John 1 says Christ is the Word. Doesn't it seem reasonable Christ is speaking of spiritual food, as the remainder of the passage clearly indicates?
I wouldn't be comfortable concluding salvation is done by a mere physical act of eating and drinking. The seems so superficial and at odds with the rest of the Bible. Scripture points to a heart conversion. Repentance and turning to Jesus for forgiveness.
If that is misguided, the the Lord has a lot of explaining to do for inconsistency.
This is also intended quite literally. For how can one be guilty of profaning the body and blood of the Lord by engaging in merely a symbolic act.
This makes clear the need for confession for grave sin (i.e. violation of 10 commandments), true sorrow for our sins, penance, and forgiveness.
Thus, all of your other concerns regarding faith and conditions to be saved, are addressed.
The rest of your questions are simply the same as those expressed in verse 60, and you are unwilling to accept the words of Christ.