Is walking included in public transport journeys?

Yes - all public transport journeys allow for walking.

The maximum walking time allowed between stations/stops is 10 minutes.

When using the API or one of the plugins, the walking_time parameter can be used to control the time allowed to walk from the origin to the first station/stop and from the final station/stop to the destination. By default this is set as 15 minutes, and this limit is applied at both ends of the journey independently (i.e it is not cumulative).