T.F.
I substitute teach in the Plano ISD. There is no way any child is allowed to use a microwave at the school where I sub.
You can get a print out of the schedule of meals for the year, usually from the home page of your school or the first week of school. You can plan out whay she likes/dislikes on certain days.
The lunches are said to be balanced but since it is a cafeteria line, a lot of kids just go through and pick their favorite items, leaving out the some of the healthy items.
A lot of children where I teach have specific days when they buy lunch, such as chicken nugget day, pizza day, etc depending on their likes.
I would suggest a good thermos. MANY kids bring soup, pasta, spagettios, etc to school. It stays warm for them.
You can change up her lunch routine with a little bit of each option.
Best wishes....They grow up SO fast.