Spell Adjudication.

It has recently become very important to me to know how Polymorph Other will be applied to PCs. Will there be a save for personality? Is personality change permanent? Can a cleric or mage still cast if speech is possible? I may have other questions based on the answers to these.

Requires a secondary saving throw to maintain their original mentality. Casting is still possible if speech and hands are present, and original mentality is still intact. Not sure if mentality is restored yet after being dispelled/polymorphed back.

Save vs what? I'm not familiar with secondary saves.

Save vs. the spell initially, then a second save if the first is failed to retain your mind in the new body. Say a hostile magic users used polymorph other on you to turn you into a frog, First you'd save vs. the spell, if passed then there would be no effect. If you failed then you'd be a frog, and need to make another saving throw to see if your mind becomes that of a frog as well.

What if the target welcomes the change? Still a save?

No primary save if it is un-resisted.

So the only real question left is if a bent mind stays bent after dispelling.

You'd have to try and see.

I suppose I will.