I don't know about pet dragons, but Ender Dragon is disabled by default. All boss mobs (the big ones) can cause issues if you wish to morph into them
Skeleton Jockey is not a seperate mob, that's just a skeleton riding a spider.
Bees, I like those. If you turn the hostility mode on on the configs you can fly near hostile mobs and they wont attack
The dev of optifine does not want their mod on any public released modpacks, so no.
It's not impossible to set the mod in the pack yourself, but the compatibility issue is with optifine itself, not the modpack.