I can tell you the grading scale at the university I work at. I think it is pretty standard but you should check with the particular school. I don't know anything about weighting for honors/AP. High school students here don't have GPAs, they get % for each course and then the % are averaged. The more competitive the program, the higher the average needed to get in. The program I work in says that a minimum of an 80% is required - last year successful applicants all had an average of 86% or higher.
90 – 100 4.3
85 – 89 4.0
80 – 84 3.7
77 – 79 3.3
73 – 76 3.0
70 – 72 2.7
67 – 69 2.3
63 – 66 2.0
60 – 63 1.7
57 – 59 1.3
53 – 56 1.0
50 – 52 0.7
< 50 0.0