I believe Windsor, Ontario is directly across from Detroit in the US. It is in Essex County. You can find more info here on the Essex County web site http://www.rootsweb.com/~onessex/
. As for marriages in Ontario it all depends on the year you want. Check out Mary Crandall's web site Ontario Marriage Registrations at http://homepages.rootsweb.com/~maryc/thisisit.htm
I hope this info helps.