While we wait for Mike to rework the character screen, most of the data you want is either on Last Epoch Build Planner or https://lastepoch.tunklab.com/
8 per hit, not sure what the cast speed is.
No minions have tooltips yet, that #### is hard since minions snapshot more than “normal” skills & you can have different minions out with different stats snapshot making the tooltip a complete Charley Foxtrot.
Have you tried the in-game game guide? Pretty sure that explains ailments & stacking.
No.
Damage from DoTs is generally consolidated into fewer numbers, though there’s currently a bug where hits/damage instances that are too close together the second number doesn’t get shown.
If that’s not a rhetorical question, maybe the first area you were trying to kill tankier mobs with more hp or magic/rare mobs with the more hp modifier, or they were within the AoE of a rare with the “allies take less damage”.
I know, Mike is working on updating the character screen (along with everything else he’s working on), while we wait most of the data is available on one/both of the sites I linked, the Game Guide helps, as does Andrew’s awesome Community Game Guide, and failing all of those, there’s other people (discord/forum).