I am a Traditional Christian, not Catholic but close so I hope it is okay for me to answer this
#purgatory – Because Scripture tells us that we will be purified I Corinthians 3:11-15. I love the way C.S. Lewis talked about Purgatory:
Our souls demand Purgatory, don’t they? Would it not break the heart if God said to us, “It is true, my son, that your breath smells and your rags drip with mud and slime, but we are charitable here and no one will upbraid you with these things, nor draw away from you. Enter into the joy.”? Should we not
reply, “With submission, sir, and if there is no objection, I’d rather be cleaned first.” “It may hurt, you know”—“Even so, sir.”
#rosary – To help contemplate what Christ went through. I myself say the Divine Mercy Chaplet
Chaplet of the Divine Mercy - Wikipedia
#transubstantiation (the conversion of the substance of the Eucharistic elements into the body and blood of Christ at consecration, only the appearances of bread and wine still remaining) – That is what Catholics have termed the Real Presence of Christ. All Traditional Christians from Anglican to Orthodox and in between believe in the Real Presence as Christ told us in the Gospels. “This is my body” and “This is my blood”
#Mary and the saints as mediators between God and me. - That is wrong, there is only one mediator between God and man. That does not mean others can not pray for us like the Holy Mother and Saints as said in Hebrews “We have a great cloud of witnesses”. Do you ask other people to pray for you when you need it? Same thing Traditional Christians such as Catholic, Orthodox, and Anglicans along with others understand that those in Heaven can pray to as seen in Revelations.
#baptism since child – Do you mean infant Baptism? This has been done since ancient times ever since the Bible times and in the Bible where they Baptized whole families.
#penance for sins – Again in the Bible.
#sacraments: - They again have been done by the Ancient Churches and you can find more information online. We do the sacraments
>initiation
baptism
confirmation
Eucharist
restored order of initiation
>sacraments of healing
penance and reconciliation
anointing of the sick
>sacraments of service
holy orders
matrimony
#demonic possessions – You don’t believe demons exist?
#apocryphal books – They are good to be read in my Church
#sign of the cross – It is a prayer