The leader of the 501st Legion's Torrent Company, CT-7567 – better known as Rex – was an exemplary clone trooper, brave under fire and dedicated to the men serving under him. As a no-nonsense, by-the-book trooper, Rex had to adjust to the maverick Jedi General Anakin Skywalker and his headstrong Padawan Ahsoka Tano.
Despite his customized armor that greatly resembled that of an ARC Trooper, Rex was a standard Clone Trooper with the rank of Captain. This means that Rex was heavily modified from the Jango Fett template like the majority of Clones and underwent conditioning meant to make him totally obedient.
Rex was a clone captain (later commander) who served as second-in-command to Jedi General Anakin Skywalker during the Clone Wars. He worked as a commanding officer in Torrent Company and the 501st Legion under Skywalker and his padawan, Ahsoka Tano.
Rex is often mistakenly refered to as "CT-7567", yet "CT" means, "Clone Trainee" for the Clone Cadets, while "CC" means, "Clone Code" for every other Clone Trooper. The scar under his chin and his character personality is modeled after Han Solo, who was also an officer under the rank of Captain.
Rex was a generation one Clone, and he was confirmed to have been at the First Battle of Geonosis. So, there's nothing saying that he couldn't have been him. If the Clone was Rex, it would explain he and Anakin were so close. After all, he would have helped Padme and helped her get reinforcements to Obi-Wan and Anakin.
Rex was added to the main cast of Star Wars Rebels television series, set fifteen years after The Clone Wars, in the second season. Now seemingly a much older man due to accelerated aging, Rex lives with fellow clone troopers Commander Wolffe and Captain Gregor.
That would be Kix. Due to his being frozen in stasis by the Separatists, he survived for 50 years after the end of the Clone Wars before being awakened by a pirate gang several years before the events of the sequel trilogy.
Interestingly enough, Rex seemed to be differently affected by Order 66, as he managed to hold off shooting Ahsoka for a while. Rex was later saved from his programming by Ahsoka and some droids that managed to remove his inhibitor chip, freeing Rex from the orders of Darth Sidious.
Jesse, also known by his designated number CT-5597, was an Advanced Recon Commando and Clone Lieutenant who served in the 501st Legion during the Clone Wars.
As night fell, Rex met with Skywalker, Windu, and Boll at Urus's palace to discuss the problem of the uncontrollable Zillo Beast with Palpatine. While the Dugs wanted to kill off the Zillo Beast, the Jedi wanted to preserve the creature, as it was one of the last of its near-extinct species.
The clone who took the name "Rex" was grown on Kamino like his fellow clone troopers, bred to be among the best soldiers in the galaxy. Rex received additional command training and earned the rank of captain, overseeing Torrent Company within the 501st Battalion.
Rex is actually 31 years old, though his biological state is likely closer to at least sixty years, due to the accelerated aging that was genetically installed in all Clone Troopers. Because of their accelerating aging, Clones age twice as faster than regular humans.
Anyway, in answer to your second question, Rex is not a Mandalorian. His armor bears a resemblance to Mandalorian armor, however, because the clone template Jango Fett wore Mandalorian armor, and the armor of clone troopers was based upon Fett's.
The clone trooper battalion, was put under the leadership of Jedi General Anakin Skywalker with clone captain Rex, while Rex was succeeded by Appo at the end of the war. The 501st was present from the beginning of the Clone Wars until Legacy Era.
Clone 99 was a clone of the bounty hunter Jango Fett, created on the planet Kamino to be a soldier of the Grand Army of the Republic. However, 99 was physically disabled due to genetic errors during the cloning process. As a result, he aged faster than his fellow clones.
As Fives pleaded with his old friends, shocktroopers led by Commander Fox burst in and ordered him to surrender. Fives panicked and grabbed one of Rex's pistols, but was shot and mortally wounded. Dying, he told Rex the conspiracy was bigger than anyone could have imagined.
Rex tells Jesse he has the situation under control, but Jesse says he must follow orders, and if Rex doesn't, he will. Rex reasons that Order 66 was to execute the Jedi, but Ahsoka is no longer a Jedi.
It's possible Cody had rationalized his actions during Order 66 by telling himself it had been necessary and would not happen again, but now he was brought face-to-face with the Empire's ongoing atrocities. Cody abandoned the Empire, apparently one of many clone troopers who deserted in the months that followed.
In 19 BBY, he fought on the planet Cato Neimoidia, flying an ARC-170 starfighter. When Order 66 was issued by Supreme Chancellor Palpatine, CT-57/11-9048 and Captain Jai'galaar killed their commanding officer, Jedi Master Plo Koon, while they were escorting him on a patrol of the planet's bridge cities.
A disillusioned clone trooper who saw too many of his fellow brothers die in combat, Cut Lawquane left the service. The deserter attempted to carve a new life for himself as a simple farmer on Saleucami, wanting only to live in peace with his wife Suu and their children, Jek and Shaeeah.
Cut Lawquane was a clone trooper who fought for the Galactic Republic during the Clone Wars. Shortly after the First Battle of Geonosis, Lawquane's transport was attacked by Separatist gunships, leaving his fellow soldiers either dead or injured. Lawquane fled, deserting the army, and later married Suu Lawquane.
