@Dimanor3
Nothing wrong with that! Indeed, the Beginner’s Shamisen is a legitimate nagauta shamisen, so you’d get the full shamisen experience with that. 
- Unfortunately not. The Beginner’s Shamisen itself doesn’t include any accessories, because we receive it directly from the maker who doesn’t include them.
- The ShamiBuddy doesn’t include a case either. I would love to have that, but I haven’t yet found a source that could provide them cheaply enough to affordably include in a set. (I don’t think I have the storage space to fit that many cases either)
- It’s pretty necessary. Because the shamisen doesn’t include anything when we receive it, I arranged that set to have all the essential basics to get started (besides bachi and koma, which are separate so the player can have more options).
- The shipping fee would be the same for either one or all items.
All together, the shipping fee is $35 (at the current time of writing this. The shipping cost should lower by 2022)
Oh yes, all you need to do is flip the strings around to make a the shamisen playable for left hand. For the full experience, adjusting the kamigoma is also something to be done, and I have instructions for that here - Can Left Handers Play Shamisen?