There is no justifiable reason why Anna and Elsa must then be separated for the rest of their lives.

That's true. Not a plot hole or anything. People aren't perfect and these parents are certainly fucked up.

Again, for no known reason, the kingdom’s gates must also be shut and nobody allowed to come in

Again, these are terrible rulers. It's just who their characters are. May as well criticize Hannibal Lecter because "eating people makes no sense."

Keep in mind that Anna is the younger sister, and thus most likely to be only 16 or 17 years old. Despite her young age, she sings about her hope to meet “the one.”

Are you really criticizing a teenage girl for being written to be obsessed with finding a boy?

supernatural powers are common in the world of “Frozen.” When they go to the trolls in the beginning, they ask if she was “born with the powers or cursed.” That means that people not only are sometimes born with powers, they also get them through a curse.

Not following your logic here at all. If my baby had powers I too would want to know if it is natural or if something happened to her. How does that imply that there are others with powers in the world? Even then, how do you know they would be accepted?

Obviously, at the end of the movie, Elsa continues to be queen and shows off her powers to everybody so they can ice skate, etc. This means that having powers does not preclude anyone from being queen. So, in other words, the whole plot revolves around the fact that Elsa has to hide her powers forever - but she actually never had to hide them at all.

Elsa ran off because she was always told by her parents that her powers had to be contained or she would be feared. When she revealed her powers, she saw looks of horrors on people's faces and had a breakdown. It's not the way it had to go down but things don't always go perfectly now do they? She has to break away from what her parents taught her (the whole point of the Let it Go sequence) before she can live in peace with everyone at the end.

Now elsa had used her powers many times as a child, and an everlasting winter was never started, so it really makes no sense that it would cause a winter every time she uses her powers.

Elsa's feelings were out of control as she had just left everyone she knew behind and was coming to grips with what was happening.

Also, we find out in the end that love is what causes the ice to melt, and also to heal somebody who gets ice in their heart. So it can be assumed that Elsa does not love Anna, or anybody, otherwise a never ending winter would have never been started.

It's possible Elsa needed to show that love in order to save Anna. The same way a character comes back to life when tears fall on them in so many pop culture depictions.

By the way, it is never explained how Anna knows that the winter is going to last forever.

shrugs character can't make assumptions?

Anna, we know, has essentially never left the castle, never done anything physically challenging that we know of, and has no experience with… anything. So it is only logical that she should head into the mountains alone, with no supplies or warm clothing, to track down her sister - even though she has no tracking skills whatsoever

I know of a boy who was drowning in the ocean and his brother, who was not a lifeguard or expert swimmer, went to try to save him and ended up drowning himself. Some people are willing to do anything for family without thinking.

During these times, disrespect such as this would be punishable by death. During the coronation everyone bows to the girls, why would Christoph now think he has no obligation to show any respect at all?

You should watch Game of Thrones. The way royalty is treated there would make ya faint!

So despite the fact that Christoph has been going in and out of the mountains his entire life, within a few minutes of them leaving he has gone directly into an area infested with wolves. Not only that, he was headed down a path that ended in a cliff. Even had the wolves not come after the couple, they still would have ended up at the huge canyon that they had to jump over. There is no way Christoph could have survived this long if he was so inept at traveling into the mountains. Either he was leading Anna to a deserted place to rob/kill her or his particular brand of psychosis caused him to temporarily forget all the trails he learned his entire life. Since he says later on that he would be okay with her dying, it’s safe to assume Christoph was in fact taking Anna somewhere to rob her and God knows what else

How do we know he doesn't take the same path all the time? How do we know they were headed in a direction towards Elsa that humans don't usually travel through?

Christoph asks “do you even know his last name? have you eaten a meal with him.” Ironically, we never learn Christophs last name, and he does not eat a meal with Anna before they are assumed to be in “true love.” Also, their relationship has only lasted the span of one entire day before true love is assumed.

Is it ever really assumed that this is true love and Anna isn't simply dating him at the end? After all, it doesn't end with their wedding.