For example Holy Communion on the hand. Some people, some priests says that is sin and its immoral. But some says everything is fine. Some people treats Mary more special, some not.
Some people, priests says that Jesus said to everyone about healing etc. And some says that said only to priests.
Who is right? Why have many different information being in one Church?
Receiving communion according to what the Church has approved is not a sin and it has approved reception “in the hand” for some places.
The Blessed Virgin Mary is venerated and is a saint. Individuals vary on their degree of veneration.
Do you mean healing of sins through the sacrament of confession? Mortal sins are forgiven through the absolution given by the priest, but may be forgiven also through perfect contrition (with the intention to confess later).
799 Whether extraordinary or simple and humble, charisms are graces of the Holy Spirit which directly or indirectly benefit the Church, ordered as they are to her building up, to the good of men, and to the needs of the world.
800 Charisms are to be accepted with gratitude by the person who receives them and by all members of the Church as well. They are a wonderfully rich grace for the apostolic vitality and for the holiness of the entire Body of Christ, provided they really are genuine gifts of the Holy Spirit and are used in full conformity with authentic promptings of this same Spirit, that is, in keeping with charity, the true measure of all charisms.
But some do have the gift of healing! Read Saint Paul in 1 Corinthians 12 about the gifts. God gives to each according with His will. We do not all get the same.
When in doubt or confusion, it is always good - everywhere and every time - to read the catechism. You cannot go wrong doing that. And, if it does not specify a teaching, then we are probably allowed to believe as we wish - as long as it is in agreement with the larger Gospel message.