Colleges understand that not all schools offer the same courses. Your dd will be evaluated based upon whether she took the most challenging courses AVAILABLE to her. If she can't take Diff Eq. in high school, I don't think that will be a big blow to her record, as long as she demonstrates that she has taken the toughest high school math in her school. She can also supplement with online, summer, or college courses according to her interests and abilities.
Latin is helpful, but I wouldn't say that every kid who takes it will ace the reading/writing portions of the SAT. If that were the case, it would probably be mandatory in all high schools!
If your dd doesn't have a sport, I would encourage her to develop a favorite in this area. It could be a team sport or something individual, like running.
Looks like a nice solid plan!
