It's cool, we're all new once.
I've never even owned an eheim filter... too expensive and for $50 less I grabbed a zoomed 501 for my mini-s. But yes, they'll fit fine. And it doesn't matter, just put the filter next to your tank. It makes no difference where the filter is.
For a filter you won't really see (no one photographs the filter lol) it doesn't make that big a difference. (Eheim IS a better filter by far though afaik