also if you think Dumbledore kept Hagrid and let Remus attend Hogwarts exclusively out of compassion and goodness of his heart or whatever, and not because he needed extremely loyal half-giant and werewolf totally…
1) Albus had no authority over the wizarding world. He couldn’t force anyone to hire Remus, and Remus himself was hiding because he felt guilty for not figuring out Sirius was a traitor, thus leaving him all alone when Sirius killed the Potters and Peter. Or so he thought.
2) First of all, at the time the Chamber opened for the first time, Albus was not the Headmaster but a mere professor. He had no authority, yet he used his influence to convince Dippet to keep Hagrid. Also, it is explicitly stated that everyone loved Tom Riddle. They thought he was the perfect man, brilliant, good, handsome. And he had never given them a reason to doubt him. And then you had the half giant in a prejudiced world where Giants are considered monsters - and they are. Of course no one would believe Albus if he said ‘No, the half giant with a weird fondness for monsters didn’t open the Chamber but the Prefect, perfect Tom Riddle who had everyone wrapped around his little finger did it.’
By the second time the Chamber was opened, no one knew Voldemort’s true identity, and Albus couldn’t prove Tom really opened the Chamber, and even if the Minister did believe him, Voldemort was considered dead so how could he open the Chamber? So that left Hagrid as the guinea pig. As powerful as Albus was, he was still just a headmaster and he had to follow the Ministry’s rules.
As for Snape, Albus didn’t trust him at first, but he trust in his love for Lily. That’s why he vouched for him; because he knew Snape would have never put her in harm’s way, and when Voldemort would come back, he could trust his rage at the man who killed his one true love.
3) You do realise Albus couldn’t force children to attend school right? Parents had the choice of home schooling their children. Remus’s parents agreed to send him to Hogwarts. That might not have been the case with other children. They might have decided it was safer for them to be home.
Besides, who said anything about Remus being the only one? He’s the only one who attended Hogwarts at the same time as Harry’s father so we know of him, but whose to say others didn’t attend the following years?
Don’t make assumptions.
Teaching position cursed, don’t warn anyone: Um, hello? How could the students know the position was cursed if there had been no warning issued? Of course you can assume they speculated and gossiped, but grown ups are supposed to be smarter and wiser; if they were not all idiots by the third time a teacher left they’d know something was up with the DADA position.
Harry was in the front lines? Have you read the books? Yes he was raised to eventually die, but Albus did everything in his power to keep him safe and away from danger! Harry on the other hand was a curious little bugger and always got himself in trouble.
Yes Dumbledore was manipulative, a little hypocritical and had serious trust issues, but he did care about people.
He wouldn’t have told Snape to kill him to spare Draco the burden of taking someone’s life.