I speak from a position of absolutely no authority, however if I were MCing I would say:
1) I would say, no. It has to happen during play. The process for set-up is pretty straightforward so I would say follow it as written, and there's already a Ghoul move 'What the Right Hand Wants' to create an additional hunger.
If a player wants their Ghoul to have that hunger straight away, then I would suggest they simply start their first scene in the middle of them getting down with their boy/girlfriend to activate their sex move.
I do foresee a bit of trouble for any Ghoul with a hunger for a readily accessible and willing partner. Given that they have to hold steady to ignore a feeding opportunity, and there will almost _always_ be a feeding opportunity, then either the Ghoul isn't going to stir much from their bedroom. And if I were MC and I thought that a Ghoul player was setting up a steady partner just to farm XP then my very first hard move would be to take their partner out of circulation.
For 2) there are a couple of things here:
a) Conditions: "If you take advantage of a Condition that someone has, while making a move against them, add 1 to your roll."
There's nothing in there to say that there's any difference between a PC making a move against a PC or an NPC. And when there is something that only applies when the target is an NPC (such as the Manipulate an NPC), the rules make it very clear that it only applies to NPCs.
Moreover, if you read the Advantage & Disadvantage section, it repeatedly states that these are all about the NPCs actions:
"NPCs act at an Advantage whenever:
}} They’re able to take advantage of a PC’s Condition
while acting against that PC.
}} You spend one of their Strings on a PC to put them
at an Advantage against that PC.
}} Something would grant the NPC +1 to their action.
}} A custom move or special rule makes them do so.
NPCs act at a Disadvantage whenever:
}} They have a Condition that would interfere
with their action.
}} Something would grant the NPC -1 to their action.
}} A custom move or special rule makes them do so."
+s and -s are applied to when a PC's action (when they make a move and roll dice). Advantages and Disadvantages are to an NPC's action. If it was the PC taking the action (turning someone on) against the NPC, then they roll and get the +1 if they can incorporate the condition in their move in the fiction.
I think whatever confusion might have arisen because Joe uses the word 'advantage' on pg. 28 in the Conditions & Forward section. However I think this is purely coincidental and entirely separate from the NPC Advantage on page 119 (which is capitalised).
b) As to the specific incident, I agree with your interpretation _however_ I would say that the +1 from the morbid condition wasn't automatic. Just as exploiting a condition in any other circumstance, the PC would only get the +1 if they could narrate the condition into the action (the Turn On move). The PC would have to explain and justify how they were leveraging the NPC's morbid interest in the PC's death into turning them on (perhaps, for example, describing the death in particularly erotic terms or emphasising particular aspects that fit in the NPC's sexual profile).