Is there a setting for displaying miles instead of kilometers on openstreetmap.org? If not, can anyone recommend an android app for driving directions - preferably free software, as in freedom - that uses osm?
Whilst the underlying map data is free, the renderings on openstreetmap.org are not entirely free, as they are there for mappers, not for map end users. You would be better searching for maps intended for end user use. Even then, servers for such maps need to be funded from somewhere.
The navigation section http://wiki.openstreetmap.org/wiki/Android#Navigation lists Android apps for navigation. Some are free, others not, others have a free version with some limitations.
By saying ‘free software’ I do not mean free in price necessarily. I mean free as in the free software movement. I am running a gapps free phone, no playstore, and I don’t even use google search. I am for donating to free software projects, as long as the software is useful.
Osmand and Maps.me are free apps that have that feature.
http://wiki.openstreetmap.org/wiki/Maps.Me
http://wiki.openstreetmap.org/wiki/OsmAnd
Osmand is available in FDroid.