Notice the word "help". You must show your work in order for help to be effective. You don't learn anything if someone else does your homework.
I'll get you started.
1) Do you have a definition of "Domain"? How long does the ball stay in the air?
2) h(t) = 45 should have two solutions. What are they? You should be good at solving quadratic equations.
3 & 4) You should know a think or two about parabolas. Find the vertex and maybe the axis of symmetry.