In Revit API, Levels of all types are represented by the DB.Level. The Level primitive in Rhino.Inside.Revit represents a Revel.
Pick Existing Level
The Levels Picker component provides a searchable list of all project Levels.
You can also use the Level Parameter to choose an existing level. Right-click the Level primitive gives access to various Level functions.
Query Levels by Criteria
The Query Levels component allows you to filter a Level by its System properties.
Query Level Types
See Modifying Types for getting Level Type Information.
Provided a Level, the Level Identity+ v1.0 component inspects the standard level properties.
Getting Level Plane
Passing a Level to a Plane component, will extract the XY plane at the levels’ elevation.
Given an Elevation the Add Level will add a Level to the Project.