Welcome to you Steffie
I have not been on this tour but I have been travelling with JY since 2006, have you looked in the review section to see if anybody has left one.
Group size does vary depending on the sort of tour. If you have a date in mind you can post in the editors board the date and tour your interested in, they might be able to tell you group size, age M/F ratio etc..
I hope someone who has been on the tour will leave you an answer
Good Luck
Cindy