Would I get into trouble if I give out "too many" A grades?
You won't get into trouble if all your students earn grades of A.  It has always been my hope that I'd have a class with all A grades, or even all A and B grades.  It has never happened.

If you "give out" all grades of A, someone, perhaps your department chair or the committee you mention, is going to ask you to explain yourself.

Your course (presumably) has a set of learning outcomes.  You should assess your students against those learning outcomes, at a level of difficulty suitable to the students' standing, e.g. a greater level of difficulty for seniors than for freshmen.  When you've done that, the grades will take care of themselves, and if everyone earns an A, you've done an outstanding job with the course!

Edit: based on the update to the question:  For the purpose of providing useful formative feedback, you need to assign a grade to each piece of work you assess.  Doing so has the added benefit of covering your posterior.  Such grades should be assigned according to a rubric that the students have seen before beginning work.  There is a brief example of developing such a rubric here.

Even in a course such as you describe, grades can be assigned granularly and with objectivity.  If you've done that, your students will thank you and your defense when questioned by chair or committee is that the students got the grades they earned and earned the grades they got.