Longboards and minimals are totally different. Minimals have "watered down" turning characteristics of shortboards, with more float and wave catching ability.
Longboards have a different style of surfing altogether. Longboards aren't just about catching more waves, it's the way you ride them as well, although most longboards are more stable and easier to catch waves on.
If you are learning, try a few minimals and longboards out. For most people, a longboard will be easier to learn on, but once you get a bit more competent, then chucking them around, riding solid waves, nose riding etc is not easy.
If you want to ride a shortboard, and can handle learning on a minimal, then that's the best way to go.
You just need to try it all, see what you like, and take it from there. There's nothing wrong with having long, short and mid range boards, and adapting your surfing to suit them.