I think you're reading into the facebook friends way too much. Don't overanalyze this and don't over analyze your behavior on FB. it's very widely used and people sometimes add others without any kind of thought being put into it. it's not a good guage as to whether you're more than acquaintences or anything.. I'd just leave it as it is and people that are interested in further pursuing a relationship or friendship will contact you somehow.

Also there is nothing strange or weird if you contact them on fb via messaging, after all they added you on their friends list.