"MY REPLY: Such as? Can you cite a source for this?"
Yes both Lactantius (c. A.D. 250 – c. 325) and Eusebius (c. A.D. 265 c.340)
"Had it been anyone else, they would have been accused of being in prelest, since Orthodoxy teaches us to ignore experiences and visions. I'm only aware of one vision he had. It's more probable now that the Church is looking for reasons to justify their having declared him a saint."
Would they? Then Holy Apostles Paul and John would be accused of prelest? along with St Stephen the proto-martyr. the many saints throughout the ages who have seen visions of some short, the nun who beheld a vision of St Ethelburh? The whole issue of visions and prelest is related to protecting people (largely monastics), it is not there to exclude all Divine visions and revelation.
Further the Church being the pillar and ground of Truth does not need retrospect reason for "declaring" someone a saint.
"I submit that nobody who is a saint would ever allow pagan temples to be built. They would trust God to unify the empire, rather than compromise the biblical teaching." You may well do so, but to be quite frank what you or I think to submit is enitrely byside the point it is what the Church as a whole which guided by God has promulgated.
"All the things you describe about Constantine could be explained by the fact he had the wherewithal (money and power) to do these things. So I see no reason to consider it virtuous, since his main concern was to preserve and unify the empire." When does having the money and wealth to do something mean it is no longer a virtuas act. "And being an Arian, he was a heretic." He was not an Arian he was Orthodox. "I do not see any evidence of theosis in Constantine. He was able to do what he did, because he had the money and power." You may not but the Church does again your private opinions are not above what the Church has held as true for the last 1700 (aprox) years.
Might I ask do you want answers to your questions as being sincerely seeking to learn regarding them? or do you wish for an opportunity to ask questions to which you already believe you have an answer which you would like to "share" with us?