Have to be honest with you, bro, I looked at that web page, and it's a novel worth of text. I'm not Christian anymore (Deist) so my curiosity doesn't exceed the amount of time it would take to read, but if you give me a tl;dr I'd read it.

You can't. The Catholic defense would be that doctrine derives from both scripture AND tradition.

I'm not Roman Catholic but Orthodox Christian. Some of these are pretty easy to explain though.

1. Vain repetitions would be more like the Buddhists etc who say "ommmmm". The words have no other purpose than to induce ones self into a trance, they also commonly used drum beats for this. If you're saying repeating a prayer is somehow evil then how do you explain the "our father"?

2. We don't believe in a Pope so no qualms there.

3. "Praying" is commonly conflated with "worshipping" to protestants, but this is not and never has been the meaning historically. It's a little strange because protestants create this definition of prayer being synonymous with worship, then use it against traditional Christians, when none of our prayers equate to worshipping saints but rather asking for help the same way you might ask a family member to ask God for mercy on your behalf.

4. In the Orthodox Church we don't believe the Church excommunicates people but rather, by joining the Church and then violating it's core tenants you have effectively excommunicated yourself. People who aren't part of the Church can't be excommunicated. It's more of a formal declaration that this person is no longer with the faith than the Church causing someone to go to hell. Like if a priest says Christ is Satan, he's already excommunicated regardless of what the Church does or doesn't say.

5. The Lord's Day isn't the same as the Sabbath. Those are two separate things. Even in the Bible if you look for the symbolism of breaking bread, you'll see it occurs in reference to Jesus specifically and occurs on the first day of the week, like Acts 20:7.

You have to understand that Catholics don't believe in Sola Scriptura because it's completely false. The Church codified the canon of scripture; ergo, she alone has the authority to interpret it, not protestants. Besides, even scripture condemns the idea of Sola Scriptura by history for one, and St. Paul himself: 2 Thess 2:14 "Therefore, brethren, stand fast; and hold the traditions which you have learned, whether by word, or by our epistle." Scripture and tradition, that is what we believe, that is what has always been taught for 2000 years, until the protestant heretics came. So, it is ludicrous to believe that every doctrine is required by scripture since scripture is only one part of divine revelation, not the whole. However, there is no Catholic doctrine contradicted by scripture, it's simply impossible because that would make God a liar.

Ok, on to your "objections".

• Excommunication

Matthew 16:18-19 "And I say to thee: That thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. and in many other places.

Sabbath

Jesus Christ rose from the dead on a Sunday. Also, we're not Jews. The Church has done this practice from the beginning, I'm surprised it's even a question. Christ revoked the old covenant and established a new one. The new sabbath is Sunday because Christ conquered death on Sunday and secured our redemption. And Acts 20:7.

The revised 10 Commandments

The prots moved them around, not us.

https://www.fisheaters.com/10commandments.html

The practice of praying to angels and saints.

https://www.scripturecatholic.com/saints-and-intercessory-prayer/

The notion they have the authority to ordain saints.

Again, I'll point you back to Matthew 16:18-19. Canonization requires a number of miracles to be performed by the saint after their death and their life determined to be one of heroic virtue. You can read plenty about this. Prior to Vatican II, at least 2 miracles were required as well as the "devil's advocate" panel during the canonization process. There is debate as to whether canonizations themselves are infallible, most theologians agree prior to Vatican II they were, but again it's still debated. Either way, I think 99.9999999% of Catholics would agree that canonizations prior to Vatican II are legitimate and trustworthy.

The rosary

Do you pray the Our Father? The Rosary is entirely scriptural. Christ was referring to pagans when he was talking about vain repetitions. Also, it's prideful to assume that all Catholics are vaingloriously repeating prayers to be seen. I would encourage you to read

and this: https://aleteia.org/2016/10/20/yes-the-rosary-is-a-completely-biblical-prayer/

Vicarius Filli Dei

This is pretty easy to answer. It English is translates to "Vicar of Christ". Meaning, Christ's representative on earth. This is consistent with Matthew 16:18-19 again. The pope has the power to bind and loose, Christ gave him this power and the keys to do it, ergo, He is Christ's vicar on earth, since Christ is reigning in Heaven and not physically present ruling over the Church on earth, except in the Eucharist.

I hope that answers your questions. I will pray for your conversion to the one, true, holy, Catholic, and apostolic faith outside of which no one is saved.

Hating the Church is pretty much all you guys can agree on. What is clear is that you don't have any theology of your own. many such cases.

Unless, of course they send photos of there junk right?