Hi! We get a lot of questions like this, so welcome to the club.
But let me answer:
1. It really is hard to pass. No matter how good looking or talented you are or may think you are, I hate to break it to you, but the reality is that you have to look amazing or be amazing at some sort of talent. Mediocre or "okay" at one of the requirements is really not acceptable to them. *deep bow* sorry! And receiving a confirmation email from them isnt actually that big a deal either... they confirm everyone who applies.
2. SM is really big on looks, but isn't that the case for everyone entertainment agency? I mean, idols that aren't good looking don't really exist. Haha :)
3. It's really great that you're willing to learn dancing, singing, etc. But what SM wants in the audition is for people who already know how to do all of that. You could be AMAZING and OUTSTANDING and singing and be okay at dancing, or be AMAZING and OUTSTANDING in dancing and be okay at singing. But you really have to be (overall) good at both. There are hundreds of people who apply and try out, so you really want to be noticed, y'know?
4. The truth is, languages don't really matter for anything. I think if you spoke Korean that would definitely be something worth presenting. But other languages... they don't really care. Just show off your talent, not your language ability.
5. Considering you can't speak Korean, you wouldn't want to be caught singing the words wrong so just stick with and English song. Again, they don't care about the language. The fact that you're already applying and trying out makes it obvious that you're a K-Pop fan. (I would also recommend singing Celine Dion, just because EVERYBODY sings Adele. It's good to be a bit different at this audition).
6. SM would most likely send you to an international school, yes. They wouldn't make their trainees suffer or anything!
7. In this day and age, especially when there are thousands of people out there who want to make it in the Korean Pop entertainment industry, there is about a 2% chance that the average person would be able to make it. You seem talented, yes, but SM wants someone who is so talented that even if they were to debut them the day they auditioned, they would still be prepared and ready to perform with talent and ability that matched a rising K-Pop star's. I don't know you, so just ask yourself this: Do you already have the ability and talent to be a K-Pop star on your own? If you say yes, then you may have a chance to make it.
But regardless of whether or not you think you'll make it, go and try the audition. It's a really great experience, especially if your going to audition again in the future after knowing what it's like.
I'm sorry I'm so honest, it's just that in this case, I felt I really should be.
I hope this helps!
~Kim