I think you’d have to be a fairly accomplished/famous photographer for someone to give you a free, all-expenses paid vacation on top of several days of whatever your fee is. I’m not saying this doesn’t happen, but I suspect it’s more of an occasional perk for already successful photographers.
If you’re not familiar with slow sync flash, then this party might not be the best opportunity to practice if you’re after successful shots. I’d personally either use ambient light if sufficient, and flash if not. Once you’re happy you have enough good images, maybe you could try slow sync then.
Looks like a digital camera using on-camera flash. The lack of red eye suggests it probably isn’t film.
Piximperfect on Youtube. He breaks down almost every video into step-by-step so you can follow along.