Hi Heidi,
Yes, we booked our meals in the same booking as the room reservation.
I would recommend you book the half board so you can enjoy both dinner and breakfast. The food was wonderful, and a true experience.
Its a good place to stay but 4 nights probably a bit long. The shimanami kaido is a 75 km ish route over 6 islands and that is the shortest route marked with a blue line. On some of the islands, the blue line route only cycles through a quarter of the island. Most of the islands have some interesting locations and beaches so can definitely take many detours. If I were you, I would rent a bike from Onomichi (either the cheaper government store or the more expensive Giant store for a better bike) and plan to stop at 2 different ryokans over the 4 nights to allow you to explore the areas but not have to cycle too far to get back to your ryokan. There is currently no fee to cross the bridges so it is easy to cross to the next island and back to your ryokan. Suminoe is approx 35 km cycle from after the ferry (which you get on with your bikes from Onomichi) and 40 km from Imabari (the usual end point) via the blue line route. To get to the Ryokan, when you get onto the island Ikuchijima, cycle approx 7 km along the blue line and you will reach a seafront. The blue line heads left and you should make a right turn. It is only a short 50 to 100 m ride to the ryokan. I cycled 7 km (using the marks on blue line to guide me re distance) and then turned on my gps. Ikuchijima was one of the islands that had lots to do and could easily spend a day just on this island. Hope this helps.
There was a toilet and wash basin in the room. The showers and onsen (hot bath) are communal, one for men and one for women. Think this is quite typical of many ryokans. It’s a gorgeous place if you want a truly traditional experience.