On the flight to Israel, madrichim will start making rooming lists for hotels. The rule is 3 people per room, no co-ed rooms (males separate from females), and you get to choose you roommates if you wish, and if you don’t have any preferences roommate/s will be assigned to your room. If you know who you would like to be in the room with friends you can tell your madrichim even before the trip, and they will be happy to put you together.