According to rosabussarna.com, "Most people go on the trip alone and come home with new friends."
Zayera Khan is a trusted writer who's taken several trips on the Rosa Bussarna as a solo traveler. You can read about her Denmark trip at: https://www.breakfastincluded.co/branded/adventures-on-the-pink-caravan-iceland-and-the-faroe-islands
According to the official website, rosabussarna.com, many vegetarians, vegans, lactose intolerant, and gluten intolerant people have traveled successfully on the Rosa Bussarna (Pink Caravan).
You should contact them if you have any special needs: info@rosabussarna.com
According to the official website, rosabussarna.com, about 20-30 passengers can fit on the bus, depending on the model.
Based on Zayera Khan's experience on the pink bus, mattresses are set up in the bus and on the roof of the bus each night. There were 2 teams on the bus. The team that sets up the roof and beds every day, and unpacks these when we travel by bus.
Every day, 3-4 people are responsible for erecting the roof truss and preparing the sleeping areas on the bus roof. Mattresses are laid out next to each other, and passengers can expect to sleep very close to each other.
According to rosabussarna.com, there are some nights where passengers will sleep inside of a simple hotel. It depends on the destination and the trip.