Most of the libertarians I run into would be totally aboard with the first clause...but would prefer no state sponsored/codified marriage. Where that state sponsorship exists, they would see no harm to allowing homos to marry each other.
Abortion is generally not supported by libertarians.
Well, it goes further than state sponsorship — it’s a matter of statism when it concerns forcing individuals to service the behavior. Homosexual marriage is a form of statism.