I apologize in advance for going a little off topic, but I just want to clarify what I understand about a valid, sacramental wedding of a Catholic to a non-Catholic. (I’m the non-Catholic, he’s the Catholic.)
You should (or must?) go through some pre-marriage counselling with your priest (or someone else?) to determine that both parties are entering this marriage with full understanding of what it means. My questions: how long does it take?
Churches usually require that you approach them at least 6 months before your planned wedding date.
Must it be at the same church where you plan to marry?
No.
Can you get a note from a priest to say you’ve completed it and then have a different priest marry you?
Yes. When you do the pre-nuptial stuff at one parish and want to marry at another parish the priest will forward all that paperwork to the bishop who will then forward it either to the parish where you wish to marry or to another bishop if the parish where you want to marry is in another diocese. That second bishop then forwards it to the parish. See why they ask for at least 6 months?

Reading further I see that you’re talking different countries so I’d allow even more time.
The Catholic party must declare that they will raise their children in the Catholic faith, and the non-Catholic party must be informed of that (and in some cases they had to agree to that). I don’t have any questions about that part.
The non-Catholic no longer has to agree. Since 1983 they only have to be informed of the Catholic’s promise.
You should get married in the Church, and if that’s not possible you can get a dispensation from a bishop. What kind of reasons are acceptable? “My family hates the Church” sounds like a better reason than “I’ve always wanted a beach wedding”

Family pressures/relationships is one of the valid reasons. I know of two cases where the brides’ grandfathers were ministers in other faiths. Dispensations were granted for those marriages to be celebrated by the grandfathers.
I don’t think the priest would request a dispensation for a beach wedding unless there was another compelling reason.
Now, more questions. Can you get married at a parish that you haven’t attended long? Like, if my bf wants to get married at his home Church in the Philippines, but we do our marriage preparation here in Korea, is that possible?
It should be. We prepare couples in Canada to marry in other countries.
Obviously we’d inform the priest of our intentions (via my bf’s mother) well ahead of time, but is the priest required to know us and check that we are entering the marriage for the right reasons himself?
No, he should receive all the original stuff from the priest who meets with you.
Also, I’ve seen a number of threads on this forum where people said, “of course, you can’t have two ceremonies.”
You can only have the vows in one of the faiths. If you had both a Catholic priest and a non-Catholic minister at your wedding (that usually happens when both the bride & groom are involved in their respective churches) you can’t have them both receive the consent and vows of the couple. It must be one or the other.
Really? Why not? (genuine question here!) If we get married in Korea, is it impossible to go home to the Philippines and have a ceremony there for his family and friends to witness?
If you’re already married you can’t expect the church to pretend you aren’t.
Or if my family can’t fly out to see me get married in Asia, is it wrong to have a second wedding in Canada? I’d certainly want to repeat the vows with my family witnessing it, not just have a reception without the formality of the wedding part. Is there some renewal of vows ceremony we could do instead, if we end up being unable to gather everyone we want at our wedding?
I don’t know if the Church would consider a renewal of vows for this reason. It would be nice if the Church had a ritual for this like it does for presenting an already baptized baby to the parish. That ritual is usually used if adopted children were already baptized or, as we’ve done, adapted to present babies of parishioners who went ‘home’ to have their babies baptized (like I did with my first 2).
I hope someone can answer a few of those questions. And sorry, OP, for hijacking your thread, but I figure the situations are similar, and the answers might help you too.