Hi Xxventanaxx! Good to hear from you and Lux!
I don’t think the adult food will cause a problem as long as she eats hay and veg – it’s when a bunny refuses to eat anything you have a problem. The adult food is less rich (0less yummy) than the baby food, so many buns, probably most, will need some time to adjust to it.
Putting her head on the ground is just a sign of relaxation. A bunny can get very flat when it relaxes! If she does it near you, she’s probably asking for pets.
As for the shedding, some sheds are more terrible than others. I brush mine with a self-cleaning slicker, I also pluck out tufts of hair with my fingers, and to finish it off, I use a lint-roller. It consumes quite a lot of gluey paper, but it’s worth it because it minimizes the hair in the environment. My buns are “normal-haired”, not lionheads, it wouldn’t work very well on long-haired buns. I use a generic brand lint-roller, name brands have too stiff glue (=better quality, but not better for bunny fur).