If I look at ACS source code covered under ADPL and apply general ideas and concepts learned from this review in products I develop, am I bound by ADPL?
No. The terms of ADPL would extend to direct or closely similar reimplementations of ACS, in Java or any other language. This would extend to close similarities at any layer of ACS: in the data model, application logic, page flow, or presentation layer.
Unfortunately, "reading the UI wireframes for ACS Java" sounds to me an awful lot like "close similarities ... in application logic, page flow, or presentation layer". Or does that only apply to code, not specifications?
Now, IANAL, and I don't want to create any difficulties here, but has there been a decision, as a project, on whether or not we're going to be able to continue to model directly off of ACS? I'd just like some guidance. Personally, until I hear otherwise and clearly from reliable sources, I am staying away from ACS 4.6 ANYTHING (code, specs, etc.). I don't particularly like to say that, but better safe than sorry...