There are people in many congregations that are not strong in their faith, and perhaps you would find some who do this. But on the whole, I think even most but-nominal Orthodox do not regularly attend other churches.
I think you'd find a number of once nominally Orthodox people in Protestant churches.
Not at all. But really, the point is that there is only one Orthodox church; there are thousands of Protestant churches, and it is because of sola scriptura.
Which isn't really true either. Through splits the Orthodox church is not one, either.
It just doesn't like to talk about those splitted-off churches. It only likes to talk about those it wants to identify ideally as "the Orthodox".
And they're not particularly consistent either. As I've cited on this board, there're some who

hold to views that are not broad, that sound rather like substitutionary atonement.
To the living Bride of Christ

. No different to how you pick your leaders really.

Calling everyone else outside the Bride of Christ isn't a great way to understand what Jesus said about such things. Lk 9:49-50
And He did - by oral tradition and the Bible.
Which oral tradition doesn't trace itself to the earliest church, and so we dispense with it. You don't. Ending up with the argument, particularly the one swirling around icons.
Certainly, and like we say, we only make icons of those with physical manifestations, such as Christ, who became man, the Holy Spirit, who appeared as a dove at the Baptism of Christ, the saints, who were men, or angels, who appear in visible form.
But of course the
visible form of the icon was never ordained by God. The manifestation of God
by Christ Himself was ordained by God. So was Christ's ascension into Heaven. His image is no longer on earth, and His icons are not so designated as an image for this time.
In point of fact there is an image of Christ designated for this time. And it's not an icon.
The only way in which God the Father is ever represented in Orthodox iconography is as one of the three messengers who visited Abraham, whom we believe represent the Holy Trinity.
And um, you're saying you're allowed to represent Jesus and the Father in imagery which you set apart as holy and venerate. On what grounds? That the Church has
always done so? Then tell me where one of the Apostles did so. Tell me where the Apostolic pattern is to make an image, set it apart as holy, and venerate it.