not the patristic writings; I value them highly as the well thought out opinions of sincere Christian men (much more by the way than the pablum from some “modern” theologians), but i do not consider them infallible Scripture like the Holy Scriptures.(Orign, got ex-communicated didn’t he?) Christ considered the OT to be Holy Scripture so i believe the same of the NT.
I like Eusebius a lot but i believe he got into controversies from time to time (but I’m no expert)
The first 4 church councils, yes. In fact, if i really had to say, the Nicene-Constantiple Creed is the absolute minimum definition of Christian beliefs
I can anticipate your next question.

Not because the councils were infallible but because they correctly by men, under the guidance if the Holy Spirit no doubt, summarized the Bible.
I don’t remember what the the last three councils you mentioned said, so I can’t comment, other than i think i have read that all Christians (i know there are a few very small churches in the middle east to the contrary) accept the first 7, at least in principle, even those who profess “no creed bu the bible” PS. I am Methodist we affirm the Nicene creed – ok, its actually the Apostles Creed – every week, but at least the Nicene Creed is in our hymnal!)
PS. yes, i know that no “official” church council recognized the already established by consensus cannon until after Nicea. You know, I’m sure, that the Muratorian Fragment got the cannon just about completely correct in 170 and my buddy Eusebius got it pretty accurately well before Anathasia in 367 and the later “official” church council.
PPS. I spell and type abominably, and don’t feel like looking it up – this forum needs a better religion spell checker!! — so don’t hold that against me