Here is an answer, not written by me, but which states what I've always understood about marriage of non-Catholics:
In general, marriages between non-Catholics, of whatever religion, are considered valid, but the situation is not as simple as it sounds because there are two kinds of marriage: natural (ordinary) marriage and supernatural (sacramental) marriage. Supernatural marriages exist only between baptized people, so marriages between two Jews or two Muslims are only natural marriages. Assuming no impediments, marriages between Jews or Muslims would be valid natural marriages. Marriages between two Protestants or two Eastern Orthodox also would be valid, presuming no impediments, but these would be supernatural (sacramental) marriages and thus indissoluble.
Sounds like you are correct that marriage between non-Baptized people is "not Sacramental", but I don't know that I would say "divorce can be encouraged." But if you mean they are not indissoluble, & thus "divorce" may be possible, sounds like that is correct, from the implication of the passage above, although not stated explicitly.
Yes this is my understanding also. Non-Catholic marriages are valid as part of natural law.
As far as divorce being an option, I think so, since it was also permissible under some circuмstances before the New Covenant.
What puzzles me is why "Protestant marriages" are considered supernatural by the author... on what grounds? Maybe he means "Anglican" or "Lutheran", but I've never heard their Sacrament of Marriage to be valid (but illicit) so far.
PS: Stubborn, I've received your pm but CI won't let me reply to you and gives me an error. I've dl'ed the file but not yet listened to it.
Thank you