Category or taxonomy set up

I have been reading every article for 2 months and cannot figure out the best way to set up my Advanced searching and/or category listings.
My site is youth sports- baseball, basketball, soccer, etc Right now I have each sport as a category. I have tried it as having each sport under sub category also. I need something that is easy for people to search depending on their needs.
I want parents to be able to search by sport, by age (5-7 years, 8-10 years etc) and by type of organization (league, club, camp etc) search by season (Fall, Winter, summer, Fall) and be able to search by zip code radius
I have tried having the listing with a drop down menu with multiple selection and if more than one option showing I get this on the listing (a:1:{i:0;s:2:”–“;} ) or something like it.
Is there a way for clients to add a listing with multiple choices in an Advanced Search category? Or am I setting it up wrong. I have tried it 25 different ways over the last few months and have almost given up.
Any help is appreciated!
My site is http://www.yspn.co