That's a pretty strong list of changes. It's good to see that feedback is being taken to heart, though I hope grenades get tweaked a bit further away from their monster beta status. Very glad to see them sticking to their guns on the ranking system and not making it a more individualistic system or going back to 1-50 (the great, dark secret is that 1-50 wasn't ever actually good as a way to display your rank or progress as a player), it's the right decision. Hopefully weapon vibration toggles being included is indicative of the ability to turn off impulse triggers - that actually needs to be an option at the OS level, I can't stand them.
I'm actually not sure how much the Hydra needed to be buffed mechanically so much as have its visual feedback tweaked. The small projectiles didn't seem to have any illumination on them prior to detonation so it was tough for players to parse what effect they were actually having. In terms of effectiveness it seemed to be more or less equivalent to a concussion rifle, maybe altered a little bit in perception by the mobility changes. When you look at a concussion rifle, or a brute shot, or the grenade launcher, though, it was always very obvious how the projectiles were behaving and how they were going to change the moment-to-moment gameplay of a fight - can't really say the same for the Hydra shots. This, I think, is actually just one of the big symptoms of a problem with how the art and design of (sort of all) 343's Halo game work (and Saber's, and to a certain extent Certain Affinity's) fail to mesh properly on the player feedback end, as though the two teams are not able to make a satisfactory compromise between graphical flair and combat readability.
(the spnkr was always going to be a legendary variant - they're not crazy enough to not have been planning to include it already, c'mon now)