There are a lot of private or permissive service roads around, so I’m not sure what highway=service implies about access. Maybe better to specify explicitly if you know.
If the public have a right to drive along it as well as walk / cycle along it (ie its a public road), then you can tag it as access=yes, which implies foot=yes etc.

If you want to specify whether there is a pavement or not, you could use the footway tag: http://wiki.openstreetmap.org/wiki/Proposed_features/Footway
Plus use the lanes or width tags to show that it is narrow.