Urgot got leg upgrades because his old skinny sticks for legs ain't looking right for his massive upper body. Though they could've just made those 4 legs thicker and called it a day; I'm guessing they added 2 extra to probably give Urgot an octopus motif (6 legs and 2 arms), which can make sense given octopuses can be pretty smart and deadly predators, or something like that. Though a more practical reason may be to simply balance his shotgun knee passive, and they may have reached the conclusion that 6 knees is better to work with than 4.
There is still Beatrice, she's just other off-screen or supposedly mixed in with the other crows, given Swain does still refer Beatrice by name, albeit in a joke where he is seen confused between which crows in front of him is Beatrice. Swain will also summon 1 crow to accompany him during the recall animation, that one is likely to be Beatrice or at least a familar or an avatar of them.
Irelia getting 6 sblades instead of 4? Idk, maybe it's because 4 is not a favoured number in Asian culture and associated with bad luck or death traditionally (both in various languages in Asia, verbal pronunciation of "4" sounds like "death"), and is only sported by ominous fellow like Jhin, and so they upped the count from 4 to 6 by adding 2 more. 6 may also be consciously chosen, given it is believed by some people, Chinese people in particular, to be a good number (in Chinese, verbal pronunciation of "6" sounds similar to "smooth", as in everything goes smoothly as desired). But that's just a theory, I have no beef on this. They could've just added the number because they think it looks cooler or something.