Re: entrance.
Yes they can DEFINITELY take party favors and work out having fun with them themselves. Alucard was also generally okay with what was going on around them. It's a bit more OPEN about things, but honestly, ship life wasn't known for the MOST privacy (though he did have more than most as captain). So y'know. They are sort of at sea. Makes sense. But yes, fun times in their room. Anisa will ... find a friend to sleep over with.
Honestly, Gabe's seen and known a lot of sex workers over the years and respects it. He'd be up for finding one they get along well with (and CANNOT get pregnant) to enjoy the company of this night. There are things he misses about millennia past. And it's nice to see that element here. And yes, he will flirt with Seivarden in particular as well. :)
This party isn't simply a sexfest. It can be attended without having sex in public. No demand to expand sex beyond you and your boyfriend. Relax. Lolol.