Blimey.. I will try and answer all these.
How often do you go on these urbex adventures?
That depends on the time of year. During the nicer weather months, its every 2-3 weeks and is a full day.
How many people usually go in your group?
Usually myself and @anidiotexplores, but occasionally @lpff joins us.
Do you ever revisit any place or is once enough?
I try not to, unless one of the others missed out for some reason. I won't do a re-write unless I missed a lot first time around.
How much do you plan your outings?
Lots, I do the planning and route. @anidiotexplores supplies many of the locations.
Is it just someone in the group gets a tip about a cool place.
@anidiotexplores is more attuned to the underground than me, which is primarily Facebook.., something I try and keep away from.