Would a bad freshman year in high school have a large effect on my chances at the Ivy League Universities?

when you said "bad freshman year" i assumed that you failed most of your classes. a 3-3.5 isnt good enough for an IVY, but just do better your next 3 years of highschool, and raise your GPA. with your GPA raised, you'll definitely have a good chance at one of the IVYs, because you seem to be involved in many things, both inside and outside of school., dont worry :)