We have a 2 story home with dry wall ceilings. We have had some leaks from the upstairs bathrooms. 1) How can I find the source of the leaks without tearing out the ceiling. 2) I have very little ability in repairing things, should I call a plumber or a contractor? 3) I think the toilet in one of the bathrooms needs to be reset. Should I do that first or go directly to a skilled plumber or contractor. Please help, I have company coming in in 3weeks.

You could rent a borescope, and make small hole in the ceiling until you find the cause of the leak.
check out the link below.
http://www.calcentron.com/Pages/provision/provision_home.htm
Hope it helps.