Is there any heter or condition for a Cohain to marry a divorced women?
If a marriage was done by a conservative rabbi with one of the witnesses being a non Jew…is the marriage considered valid? Does it matter if there are no children from the marriage?
A kohen may not marry a divorced woman. Rav Moshe Feinstein discusses in several places the validitiy or otherwise of reform and conservative marriage ceremonies. Individual circumstances must be referred to an experienced Posek.
(Whether there were children from such a marriage is not an issue halachically.)