SIUE major information?

I want to go to SIUE (Southern Illinois University-Edwardsville) and I have a few questions. After completeing the ACT (my test date is April9) how soon after can I apply for SIUE? Also, I know I won't do that well on the science portion of the test but I'll do fine everywhere else? What classes, besides science, would they suggest I take? I want to be a veterinarian but major in music and performing arts. I really want to join a theater group and choir as well and continue keyboard, piano and singing lessons. I'd also like to better my reading ability and comprehension skills and creative writing. What are the classes every Freshman will have to take and how soon can I get involved with musical theater and joining the choir?