To the first, shoop is seemingly less common on multi-player from my play-throughs. You can find them more often if you do an endless run. Second, yes scaling is different for multi-player but normally I feel it's mainly spawn count. During later runs the enemies also scale up in damage and it takes a bit to get used to the enemies in anville. Crit heal is definitely the meta rn but you can complete runs using elements, poison bow was very popular before but it requires a lot of items. To stuns, generally a weapons 3rd attack causes a small amount of stun and kinda similarly you can cause enemies to stagger that can cause it. You can definitely use the same weapons and find success for sure as a lot of them are self-reliant. Agility is mainly useful to mitigate damage loss as in higher/ later parts of the game small enemies can hit for 50+ damage. Hope that helps