There are no charges to walk off the ship. You just come and go as you please. Usually, there's a lot you can see just by walking around the area where the ship has docked. What stops is the ship making?
You'll be ok in inside rooms. You're really just in there to sleep and change clothes. Take a night light for each room, as it's really very, very dark. Your eyes never adjust to the darkness.
Keep an eye on the cruise prices, or ask your travel agent to do it. It's possible that prices on an Ocean View room are not that different from an inside, in case you're considering switching.