Lifedrinker was a way to add -even more- damage to your attack roll, came online at level 12 I believe, and is something you're likely confusing for Hexblade's immediate feature that lets you use CHR as your melee stat for rolls and damage.
Cant say i see the difference ...
Lifedrinker adds your Charisma modifier to your weapon damage ...
Feature that Larian tunes Pact of Blade so it gives your Charisma modififer to your weapon damage ...
What interests me tho, is if we will have option to have both. >:]
As for Thirsting Blade, yes that's likely being blended into Pact of the Blade
Indeed ...
Important question tho, is same as abowe ... but i gues tree attacks with single action on level 5 would be kinda too much, so this invocation will most likely be left out.

Or obtained automaticly ... depends on point of view.