Raquel Usual in every wedding, specially at the ends. In the party dance there is always some drunk slut making smiles at other boyfriends.
And it happens at weddings regardless of social class.
Not where I live. I have rarely heared of people who created on someone else's wedding. Definitely not a common thing. Maybe the groups you see are to limited because of rules without a solid reason in the background and therefore the womans are not used to thinking for themselves and therefore do something that shouldn't be done, especially on a wedding.