first of all, you shouldn't use after effects as your editing program. premiere is for editing, after effects is only for doing stuff to single clips then exporting them and editing them in premiere.
also, you don't need to shoot at 30 fps. if you're shooting at 60 fps, that's fine. you need to check your project settings to make sure your timeline matches the frame rate of your clips. if it is slower, the clips will play back in slow motion.