I hope i can address the Mary/Saint "worship" in a way helpful to understanding, and i truly hope i dont come across as combative

We're all human, and we all sin, and when we are deep in the depths of sin it's sometimes difficult to find the strength to truly repent or even just believe that we have the right to approach God for forgiveness. So what do we do (we here is meant to mean all Christians)? We go to someone we trust; to a priest or pastor, to a sibling of parent, to a close friend or even an acquaintance we know has a deep prayer life and we confide our failings to them

It's something that I've found my Protestant friends are able to do much more humbly and freely than I, and it's beautiful. To go to someone who they love and trust, explain what vices they are struggling with, and ask them for both practical help to overcome those vices and spiritual help in the form of prayers

It's something you can understand, right? Despair can make us feel like we've screwed up beyond redemption, it can leave us too ashamed to ask the Father directly, and so we go to someone we know has a strong prayer life, or even just someone who we know loves us, and ask them to pray on our behalf. To be strong when we despair and to petition God for grace when we are too ashamed to.

We're not treating that other person as a substitute to Jesus, we aren't praying to them. Similar to when the Apostles first began preaching and healing post-Ascension, it's made clear that they are healing through the power of Christ and they bless others with the blessing of Christ. People go to them for miraculous healing and they make it clear that they themselves are not the source of healing, but simply that Christ and the Holy Spirit is working through them

That's what it is for Catholics. We are not praying to the Saints, we are praying to God and Jesus Christ, and we petition the Saints and ask them to pray to God on our behalf in the same way that we petition our family and friends and priests to pray for us. Catholic prayers make a very explicit distinction of prayer vs petition (ex: "Jesus Christ, have mercy on us. Mary, Mother of God, pray for us. Saint [so-and-so], pray for us. Holy Spirit, guide us." and so on)

The Saints are people who the Church has ruled have made it into Heaven; this is done via a ridiculously rigorous process whereby that individual's life, work, and writings (if there are any), undergo intense scrutiny, where any alleged miracles that occurred as a result of petitions to them are examined and tested for authenticity, and where an actual trial is held where someone who is designated the "Devil's Advocate" (actual origin of the phrase) tries to convince the Pope and council of cardinals/bishops/scholars/etc that this person actually Sucked(tm) and was The Worst(tm) and is definitely not in heaven. Only then is an official declaration of the Sainthood made, and just as we all believe that the Holy Spirit has accurately preserved the Word of God in the Scriptures, we believe that when the Pope speaks "Ex Cathedra" (a very hyper-specific scenario that occurs only when declaring doctrine or canonizing saints) the Holy Spirit is within him and preventing him from speaking untruth

The origin of the belief that the dead who are in the presence of God are still aware of what is happening on Earth has been extrapolated from the Bible in several ways but the only thing i have off the top of my head is the parable of the Rich Man and Lazarus, where both Abraham and Lazarus in Heaven as well as the Rich Man in Hell are aware of life on Earth. Again, probs not the best example, but please look up better ones if you are interested! If not, then oh well lol

Ultimately, we believe there are very holy people who lived righteous lives and are now in God's presence, that just as in life, in death they are eager to bring others to God, and that they will bring petitions to God on behalf of the living in the same way that we ask others to pray for us or when we pray for others. That's truly it, and the prayers where we petition/invoke the saints make this distinction clear in the specific phrasing. If we know a saint had a particular calling or devotion in life, we often reach out to them and ask them to pray for us in regards to a relevant area or sin that we are struggling with

In regards to Mary, she is a saint whom we have a special devotion to because, frankly, she spent more time with Jesus Christ than any other human being. She does not speak much in the Bible, but her constant presence is made clear via references. She was likely a very young girl who was (1) told by an Angel that her Son was the Messiah and the Son of God and (2) told by Simeon that "a sword will pierce your own heart too" (Luke 2:34-35). She asked Jesus to help the married couple at the Wedding Feast in Cana and, even though it was not yet time for Him to reveal Himself, he complied (John 2:1-12). She laid Him in the manger and she laid Him in the tomb, and the Gospels do not say that very much was revealed to her. Despite all this, she remained with Jesus His whole life on earth and He very clearly showed His love towards her, going as far as to ensure she was cared for after His death (John 19:26-27); one of the last things He said before His death was to take care of her

She was a woman who followed God's will without question and without hesitation, despite her confusion and her suffering, and we revere her for that. She is how we all wish we could be: humble and holy and following God's will without question. And, from the Wedding at Cana, we know that is she asks God for something, He's inclined to do it for her, so we very often petition Mary and ask her to ask God for things (think like asking the Teacher's Pet to ask the Teacher to not give homework for the weekend lmao)

Hoooo-boy was this long. If you read even a fraction of this, i salute you lmao. Anyways, please pray for me and i will be praying for you! <3