In all of my years as a believing Trinitarian, around Trinitarians, participating on various Christian forums, I've
never heard anyone use those phrases or imply them. Please provide an example.
Also, I've explained what I believe, and provided two links that explain what we believe. There are plenty of books, articles, and websites on what we believe in relation to the Trinity.
Yes.
And they would be incorrect for doing so.
Both. The Trinity is comprised of two ideas, to put it simply: "who" and "what". The Father, Son, and Holy Spirit are "three" in regards to "who", and are "one" in relation to "what". When we understand this, we see that the Trinity is not a contradiction as is often stated, because the oneness and threeness of the Trinity are talking about two different concepts.
In regards to the idea of "relationship", the Father, Son, and Holy Spirit are three distinct Persons, and they eternally exist as a relationship.
Ok. I don't think what I posted in that paragraph is complicated. Essentially, we don't believe there are degrees of Godhood or that someone can be more or less God than another. The fulness of Godhood dwelled in Jesus.
You're entitled to your opinion. I especially found the first article outstanding, as it explains what we believe as Trinitarians, what we believe on what "substance" (or essence, or nature, or being, all used interchangeably) is, what "person" is, Biblical bases, etc.
Trinitarians believe that the one God eternally exists as three distinct Persons. There would be three chairs.
Another article that I find great is this one:
http://www.ignatiusinsight.com/features2011/fsheed_trinityts_may2011.asp
It is by Frank Sheed, a Catholic, who wrote the popular book "Theology and Sanity". It includes chapters on the Trinity that explain it so greatly that many buy the book just for that. I believe part or all of it (it's been awhile since I read the book) is reproduced in that link.