1. We don't have any evidence that Superboy Prime with the Anti-monitor's armor is more powerful than the Anti-Monitor. It's just speculation. Speculation means that it isn't true.
No, his bio, from DC themselves say he is 'more of a threat than the Anti-Monitor'.
I'm not sure that counts as speculation.
If it said in Odin's bio in the Marvel Handbook that he would mop Galactus in a fight. No one would doubt it then. Why does it not count when DC says it?