For the back surgery? I live in London, procedure was done under the National Health Service at the Royal Free Hospital, Hampstead. Doubt that information will be of any use to you.
For the kidney stones? Went to the BLUFF Clinic in Yokohama (corrected). The physician I saw spoke excellent English, knew immediately what was wrong, gave me painkillers strong enough to really help and warned me that I might get an infection and what the signs would be, which proved very useful back in London.
Mr Sato, the concierge at the IC, was also wonderful. His colleagues, whilst polite, just weren't the same calibre.

This hotel charges a premium for ocean view rooms and they are regarded as a higher category. But not by me. 16 days by myself looking out onto a horizonless expanse of grey would dampen my mood. The city view is much more cheerful and quite spectacular in its own way. Didn't matter to me that the room they offered to upgrade me to was more expensive and a higher category, the actual room itself was the same (had colleagues with me who were booked into these ocean view rooms, they liked the view from my room better too).

Not really. There ARE convenience stores around, and there is a bakery close to the entrance of the nearest train station (not sure if you can use a cc to buy baked goods, you'll need to take cash around with you and 7-11 ATMs are one of the few places you can reliably withdraw cash). At the IC Hotel you are perfectly positioned for conference facilities, everything costs that little bit more, it's just like being in the middle of a major metropolitan financial district. Not that easy to get fresh fruit in this corner of Yokohama.
If you are looking to save some money during your stay you might want to figure out the closing times at the big department stores at the main Yokohama station and go visit a half an hour or so before they close. This is a way to get discounted foods (particularly bento) and fresh fruit.

Talk to Mr Sato (if he's still the head concierge) and figure out if you need any signs to show people selling food. Not sure if there are any restrictions you need to follow with regards to your stomach.

That's lucky then. You will have to walk for hours but you won't have to climb many stairs and the area is very flat. As for stressful environment - walking through a shopping mall doesn't fit into everyone's idea of "relaxing times", but you can walk along the outside if you want to avoid the shops and the shoppers. At least you have the option to go inside if and when the weather gets bad.