My “competing and very diverse Christianities” describes more the time in the first and second centuries
Epiphanius apparently detailed 80 'heresies'. Were they all Christian, or included pagan beliefs? Is his Panarion available online?
From Roger Pearse`s site
Bishop Epiphanius of Salamis wrote a huge work in 3 books cataloguing 80 heresies. The work has recently been translated into English for the first time - the only complete translation in a modern language. (Copyright prevents more than extracts being made available). The title of the work is Panarion, meaning Medicine-chest, but the Latin translations of the 16th century had the title Adversus Haereses, meaning Against the heresies.
I doubt there are any originals. There are no originals of any of the books of the Bible or just about anything that old. All we have are copies of copies, though some of those copies are pretty old themselves.
However, we have more than quotes from Eusebius. We do have entire manuscripts of many of the early church writings. Where all we have is quotes, the quotes tend to be compiled together as "fragments of Papias" or something like that. A book like the letter to Diognetus will come from various manuscripts, maybe only three or four, of various quality, but it is not just pieced together from quotes in other writings.
Sorry, I don't know. The best I can come up with is in the wikipedia article. It says:
Arius was possibly of Libyan descent. His father's name is given as Ammonius. ... Although the character of Arius has been severely assailed by his opponents, Arius appears to have been a man of personal ascetic character, pure morals, and decided convictions. Warren H. Carroll (paraphrasing Epiphanius of Salamis, an opponent of Arius) describes him as “tall and lean, of distinguished appearance and polished address. Women doted on him, charmed by his beautiful manners, touched by his appearance of asceticism. Men were impressed by his aura of intellectual superiority.”