First of all, if you want to make this a quality haunt, I'd wait till next year, there's not enough time. But, If you want to do it this year:
What are you making the walls out of? Black plastic drenched w/ fire retardent is good.
As far as "stops" , there are many possibilities. Props can come pretty cheap if you have a good imagination. Also, got to your local part store and look for stuff called "Halloween Scene setters", they are rolls of scenery and look great.
Look online to get some haunted house scene ideas.
Clamp and strobe lights work great.
Check w/ your fire dept, before building anything.
Have security staff there as well as, technical and scary staff.
Confine groups to 8-10 people at the most. Count off 30 sec between each group. (depeding on the lengnth of the haunt)
If you have any specific questions, PM me
"If you fail to plan, plan to fail"