I am yet to find a university that cares about a weighted GPA. My high school doesn’t weight GPA’s at all so an A in a regular class has the same value as an A in an AP/Honors class, gpa wise. Many colleges look at the rigor of classes you take and put that into consideration but they’ll almost always ask for your unweighted GPA because it’s more consistent through out schools in the country.
As far as admissions committee looking at a Arts High school differently, most of the time it’s separate. When you send in your test scores and transcripts it gets reviewed by the same people who are looking at any other major at the university. It’s normally two different decisions that go on for academic and artistic so when you are just trying to get admitted to the school first, it’s basically the same as any other math or science major. Of course, like everything else in this process it can vary among schools.