So happy you are loving your ShamiBuddy!
Good question! Well, it’s usually best to remove it from the strings, as removing tension from the strings increases the life of them. However, rather than completely removing the koma from the ShamiBuddy, you can just slide it to the side so that the thickest string pinches the edge of the koma, holding it in place. (Let me know if that makes sense, I can send a picture if not)
It shouldn’t require any maintenance, although dusting with a damp cloth is totally fine.
Good point! Yes, I think we’ll have replacement parts in the future for itomaki, but it should be known that the strings included is the ‘Ito Set (Nagauta)’ in the Bachido Store, and any koma in the store will work for the ShamiBuddy (and in my opinion, it makes the ShamiBuddy sound better too)