Translation:You need to go to school.
Does this sentence both mean that school is important, you have to go there and the physical act of walking instead of for instance driving.
Physical act of walking.
First two. The last one (walking) sounds odd here. I'd say "Тобі треба/прийдеться іти в школу пішки"
"You have to go to school" sounds equivalent to this native speaker's ear.