After just looking through the beginning of the two solo any% runs, I noticed that there wasn't a similar strat, Is this just a case of personal preference or there being no calculations done to see what the most effective strategy is? I also noticed that both used the war mage, but could the sorceress also be viable? Just a few questions I have because I'm thinking of trying to run this game.

i think in solo the warmage would be better, in NG+ the sorceress is good mixed with the WM.

but to answer your question i dont think any real strat has been made imo

Is new game plus just using unlocks from previous runs?

NG+ mean using a file with everything unlocked from previous runs yes.

NG mean new game, started from a fresh file.