Trying to respond to all of the above without a dozen spoiler tags:
We know the guy at the end is Boba Fett because the clone troopers underwent accelerated aging. For example, the white-bearded old fellow fighting with the rebels on Endor in "Return of the Jedi" is supposedly meant to be an aged Captain Rex.
Boba Fett - just like the clone troopers - is a clone of Jango Fett, but he wasn't modified and ages naturally. The clone trooper program was also discontinued shortly after the Empire was established, so there aren't any younger clones around that would match the age of the guy seen in that episode.
Also, his armor must have gotten out of the Sarlacc somehow.
So yeah, that's definitely Boba.
And krayt dragons have been a thing in the Star Wars universe since the very first movie: when C3PO was wandering around in Tatooine's desert after he and R2D2 had escaped from the Blockade Runner, there was a krayt dragon skeleton in the background of that scene. Also, in Obi Wan Kenobi's introduction scene, he mimicked the cry of a krayt dragon to scare the Tusken Raiders that had captured Luke Skywalker. So we now have an on-screen explanation for why that trick worked - after 43 years!
Another nice throwback is the R5 unit seen when the Mandalorian returns to Tatooine, it's the same one the Jawas tried to sell to Uncle Owen in Episode 4. Apparently, someone repaired its motivator.