I'm homeschooled abroad and wrt to admin and stuff, it's not really a problem. I assume you're not a US citizen so you just fill out the international supplement. And of course, the homeschool supplement, and normally you can use that to fill out your rationale and a simple description of the kind of homeschooling you used.
Narrative transcripts are okay, but cause they tend to be longer, make sure they're organised! You can always give your classes names and compile that into a master transcript, then send in the narrative to explain each class. GPA isn't technically necessary, but I do know that many schools (in particular, public ones) do require you to have a grade in all the courses, more a formality than anything.
You mentioned a booklist. I'd submit that attached with the narrative transcript, leave the additional info for something nonacademic to sell yourself, like geekmom said!
I suppose at a less competitive school, just having a transcript and SAT scores would be okay for admission, but some of the top tier schools require SAT subject tests from all applicants, and there are others that require SAT subject tests from all homeschoolers. AP exams are probably not available to you overseas, I've had the same problem too, so I took lots of subject tests. It works for me cause my curriculum covers the stuff tested and I never re-studied for the tests.
Most schools require that when you apply you must have taken courses in english, math, science etc. Even if you're an unschooler, you must have covered this curriculum, yeah? It'll probably overlap to some extent. Especially if you speak another language apart from English, maybe a native language for you, you should take the subject test for it! No need to study if it's native for you
As to your belief that taking SAT subject tests is pointless, I'd disagree with you on this. If the tests you're taking is related to your major, you'd find the knowledge pretty valuable. You don't need to cram for it, really. As long as you've been studying pretty rigorously, you'll do fine!
Best of luck!