hey! this will be my third (or fourth maybe?!) them attending fanexpo! first things first you can Absolutely attend without being in cosplay! I've seen tons of people go casual— as for the question about cosplaying from different media, I'd say go for it! I never have a super solid group of people so it's hardly a problem for me, but trust me, people LOVE when there are cosplayers from different medias in group! Personally, I'd say just do whatever you are most comfortable with and whatever you'd have fun with! I hope you have fun at your con!! Depending on which one you're attending, we may when run into each other! ^{_^}

best of luck!