Facebook posts and privacy?

[Kayla]

I posted a status to my wall giving my skype account name out, and got about 13 requests from people /not/ on my friends list. I don't care to be honest, just curious as to how these people found me.
XD It's quite annoying though, to have random people trying to add me (all of which I declined)
My posts are set to public, but how are these people seeing my posts?
I deleted the post and people are still adding me.....

[Terence]

You deleted the post from your timeline, but it is there in your friends newsfeed. after some times it will delete from their newsfeed. Those people who sent you requests are your followers or friends of friends.

[Daniel]

its Because it Was Set to Public And Somebody Got your Username Once you Give out your Username Anyone Can Send you a Request Becareful When Giving Out your Username Information