I'm fairly sure that I want "Skilled" (and the 17INT headband I've looted from the Ogre) for Miss Dark, Mysterious and Dangerous to Know - Shadowheart.
Depends ...
Do you play often as her rather than your char?
The only skill your followers are actually using is Perception ...
Anything else is only for curently controlled party member.
As the Party Sapper she will get Proficiencies in Perception (to find the traps before they find her :)) and Nature. This way between her and Gale I've got all INT Skills covered, all at +5 for combined Proficiency and Attribute bonuses.
Three WIZ Skills - Animal Handling (pass), Medicine and Survival .
Same coment as abowe.
Either I am missing something but Medicine seems to have 100% success rate when Assisting 0HP comrades
There is no skill check ...
As it is now, Help is instant guaranted return to 1HP.
Is INT 18 at such a low level game worthwhile?
Yes.
Increase CON and WIS for the +1 to Saving Throws there?
Possible ... but Int is still better.
Not many enemies bother with CC.
Light Armour Proficiency to free up a Spell Slot? One can never have too many Fireballs ...
Indeed ...
But there is no reason for casting Mage Armor with level 3 spellslot, since it dont upscale. :-/
Also, there is lots and lots of scrolls with mage armor to cover each encounter.
However, 18INT would give him that extra spell anyway ... and increase spell lethality (?).
Yes.
Magic Initiate - Cleric? For extra spellcasting.
I think those spells should be casted with Wisdom ... that dont sound effective.
Or Magic Initiate - Warlock? Are these spells regained at Short Rest?
I dont think so, no.
But if you dont use any Concentration spells, you can allways take Hex and Eldrich Blast ... but then, why dont play Warlock instead.

What about "Tough" for the 8/10 HP boost?
In my experience enemies in EA either crush you like a bug ... or you crush them with simmilar lack of difficiulty.
So ... not worth it.
16DEX for boost to AC, Saving Throws and crossbow shots "when you run out of spells"?
When you run out of spellslots ... you start casting Cantrips ... no Crossbow is as strong as Firebolt.
