Yes they rent bikes.
The boat travels from OKW to SSR to DD to SSR to OKW, so depending on which direction the boat is traveling when you catch it, you'll either go to OKW or to DD
Yes you can walk to OKW by connecting to the OKW footpath. At SSR go to the boat dock, but then continue along the water's edge (following the shared golf-cart path) and cross the bridge over the water. After crossing, take an immediate right turn and follow the footpath to OKW. The path from OKW is 0.93 miles to the water tower at HoB. From the SSR boat dock it would be a little shorter. I would estimate about 0.75 mile.