Given that Picard turned down the position of Commandant (and promotion to Admiral) to remain on the Enterprise; I think that it would be perfect for him to take up that position in the story.

To be honest, it just never made much sense to me why the Cryptic story had him become an ambassador to Vulcan.....maybe it's just me but that just seems a........weak way to write out his character.....

An ambassadorial post feels quite right to me as a logical step for Picard if he were ever to leave a captain's chair - certainly more so than accepting a promotion to admiral. He was, after all, portrayed as an accomplished diplomat in his own right during TNG. Being posted on Vulcan, though, does seem like a waste of his talents; surely a more "challenging" post would have made more sense.

I think the positions of Commandant and Superintendent of Starfleet Academy should be filled by new characters. I just feel that it would be better to try to get away from established characters....(for numerous reasons).

As far as Picard becoming an ambassador....

I always pictured him retiring to a life of archaeology, and study. Maybe stopping by the Baku homeworld every once in a while to say hi to Anij. The whole idea of him becoming Ambassador to Vulcan seems odd to me.

I don't know about any one else but the collage I went to had a "Dean of Students" and a "President"
No Headmaster just saying

That also feels just as likely to me - right up there with the possible future we saw in "All Good Things," too, where he had retired to his family vineyard. If, however, he wasn't ready to retire, and if his Starfleet career came to a point where it was insisted that he be promoted, or if he was simply asked by, say, the Federation President or another high-ranking official (duty first is the Picard way, after all), ambassador seems plausible to me.

Your humility is awe-inspiring.

Exactly. A "headmaster" is a term generally associated with religious institutions. That's why Potter uses it.

Presidents and Dean of Students are for regular college and universities.

Superintendents and Commandants are for military institutions. Like I said, The Citadel, West Point, Air Force Academy, and War Colleges use this system.

Or its the fact that British Schools use the term HeadMaster? I went to a non-religious secondary [high school] and the head of school was called HeadMaster/Mistress

No, I like the way I said it better.

Cryptic didn't write Picard as Ambassador to Vulcan, Michael Ocri who wrote Star trek 2009 for JJ abrahms did.

The story was used for "Countdown" the mini series comic that prequaled the film. Picard's role as Vulcan's Ambassador was scripted so he had a direct link to the events of Nero and the Hobus disaster.

And before anyone yells "comic- not canon" actually--it is arguably canon, as it's events are acknowledged by CBS and used to tie in TNG era to STO. Data and the Enterprise crew even wear the STO default uniforms (well, one of them).

JJ has gone on record to say he considers the mini series canon in his mind, as it was written by his request as "a gift for the fans" to tie in TNG to his story in the film.

Aside from that- I agree with OP the Commandant title can be easily fixed by Cryptic properly.