Hey Elanthil01, boy am I late to this party. I like to think of myself as a 'cutscene' expert, as the mod I just finished has 3-4 HUGE cutscenes in them. I'm pretty sure I can help you 100% on this. So here goes, I will comment on every layer of your above post:
-Set up a quest with a high priority and starts enabled (say 75 priority?) ; Is this to run the cutscene script from? I generally do it from a nearby object, perhaps what the player activated to begin the cutscene. (like a switch or computer) Is this a cutscene that is randomly triggered no matter where you are in the world, or from one specific place?
Detect if player has completed character rebuild 'quest' (VCG04 I think?)-not sure how to do this. ; You could use a http://geck.gamesas.com/index.php/GetStage for this, and look in the geck to see what the stage is if they have completed it, also perhaps a http://geck.gamesas.com/index.php/GetQuestVariable if its a quest variable that determines this.
Black screen (fast)-need to know the sfx for this one ; You need to set up an http://geck.gamesas.com/index.php/ImageSpace_Modifier for this. (Under Special Effects in the object window) That page describes all the parameters for setting one up.
freeze player controls ; This can be done with http://geck.gamesas.com/index.php/DisablePlayerControls.
move player and rotate. ; Set up an Xmarker heading where you want the player, then use a http://geck.gamesas.com/index.php/MoveTo to place them there.
screen fade in. ; Time the above ISFX (Imagespace modifier, or Effect) to fade in now.
Ghoul standing in front of player.
ghoul says something (whats this command...not a dialog conversation, just a 'say it to him' thing) ; This is done with http://geck.gamesas.com/index.php/SayTo.
Ghoul moves to chair and sits. ; Give the ghoul two packages, one to stand there and one to sit in the chair. Then in your timed stage script (which I can explain later if needed) swap the variable controlling his package and use http://geck.gamesas.com/index.php/Evp to make him do it immediately.
Ghoul enters 'true' conversation mode. ; Give him a http://geck.gamesas.com/index.php/Dialogue_Package and again use http://geck.gamesas.com/index.php/Evp to make him use it.
"Our story begins with our hapless hero diligently scouring the western wastes for wrongs to right, rights to wrong, and a pair of spurs that actually jingles and jangles. Little could he suspect that, 500 miles seaward the bleakest cloud of his weathered existance was gathering.
And now, we proudly present, "Dream a little dream"...
Screen fades to black, player is returned to where they were. ; Again, another ISM, and MoveTo.
Play a 5 second timer to give the system time to settle down. ; This can easily be added to the script.
Spawn an NPC 700 units behind player, invulnerable, ignores combat, package set to intercept player and do a forced greet, initiate dialog. (not sure on this one either). ; For this you just might want to have it enable a pre-placed NPC somewhere in the wasteland, so it takes some time for them to get there, but they wont be out of bound or through a wall or in a building or something.
NPC is a wanderer like the player.
I have some things to go do at the moment, so I cannot help you with the rest right now, but I'll be back later to do so. Let me know if you have any questions of what I have explained so far.