I got into Pokemon in around 2015 after exposure from my friends about it, and I used to play those mobile games they had and watched the anime till I got Pokemon Sun and Moon for Christmas in 2016, and since then I've played all the 3d games and the virtual console games along with R/S/E.
Yeah they'll still give you the same basic stuff, there's just some exclusive items given by either depending on the path you choose that aren't needed for the other.
Choosing either teams basically splits the game into two paths with unique experiences and sidequests depending on which path you choose, being different until when the game will be finished, giving the current demo a lot of replay value.
I dont know if the resource pack has been updated to have them yet, but I know the latest version of the game has them within the game's graphics folder.
Yeah this seems to be a bug that's appearing frequently. Our programmers are currently trying to fix the bug as there has been several instances of this happening, so please hang on for a little bit before we try to get the update out asap.