I've been on the PhD admissions committee for the Berkeley CS PhD program. Students in many areas are, for all practical purposes, admitted by an advisor. It's not a formal arrangement in the same sense as European programs, but no one gets admitted unless at least one professor will commit to being willing to advise and fund you. For superstar students this is rarely an issue and you have your pick of advisors, but for many admits there is exactly one professor who's identified your background and interests as a good fit, so you're essentially admitted with the expectation you'll work with that professor.
Nothing you say is wrong; you're correct that everyone has to do course requirements. But culturally the course requirements are treated as a distraction from research, and students are expected to start working primarily on research from their first semester. I think this is more or less the case in all top American CS PhD programs, and there are reasons to set things up this way, but it's a very different environment from PhDs in most other fields.
Thank you for the insight. Would you be willing to elaborate a bit on finding a good match for advisor, and perhaps any thoughts on approaching someone about exploring an advisorship?
First step is to be acquainted with their previous research. Understand the direction they are taking and what their interests are. Find advisors whose work you think you can build on through your PhD. Write down what you are interested in working on and how it relates/expands/builds on your potential advisor's. Then contact them sharing just that and start having a conversation - they will surely have feedback and ideas for directions that your research could take.
Nothing you say is wrong; you're correct that everyone has to do course requirements. But culturally the course requirements are treated as a distraction from research, and students are expected to start working primarily on research from their first semester. I think this is more or less the case in all top American CS PhD programs, and there are reasons to set things up this way, but it's a very different environment from PhDs in most other fields.