Yeah to be honest, there aren't many design majors around, still I don't think that should be a deterrent as long as you aim for a good design school in US.
It works like how a community college works. You take subjects that can be transferred into the university of your choice, why it exist is because community colleges credits are cheaper, this way you save money as you would do less credits in university cause you've cleared some of the subjects in college.
Most ppl do the foundational subjects in college and transfer to university.
I'm not sure how US's architecture program works, can't help you with this, sorry.
But overseas, the fees are indeed high.
The American system is fantastic for people who wants a balance and a change from the rigid British system.

A balance, which is why they require you to take subjects from a broad spectrum because Americans view education not as a specialization that leads to jobs but they want the students to also learn how to appreciate the finer things in life, which is why there's subjects like music and theater.

Subjects like philosophy, sociology and anthropology opens a student's mind to do actual thinking instead of just swallowing hard cold facts and regurgitating them out for exams.
My sociology lecturer told the class today during our first lesson,
"If you're not into thinking or are too lazy to think, drop this subject!"
Because you will fail.

And who says economics is not useful in our lives, regardless whether one majors in Chemical Engineering or Psychology, some knowledge regarding accounting and economics are highly useful.

Regarding no. 3 that's why its important to pick a uni as soon as possible.

In my humble opinion, the British system prepares graduates for jobs while the American system prepare their graduates for life.
This is of course a very subjective issue because everyone has their own opinions and they all differ as how mine differs from kim0215 so no flaming please.

i was a scholarship holder for adp and insisted to drop the stupid philosophy.
finally end up with argue with the office in school
haha
i said economics is not related and useful for that career,doesnt mean that it's not a useful knowledge,just give an example.u don't like to comment about eco,we can take account as an example too
haha.
so fast pick the uni also no use,cos some uni will not tell which is accepted until u send them ur transcript