Currently, the Kendo UI Calendar widget supports only a single selection behavior. The Multi-selection is still under consideration and it will be great if you cast your vote for this functionality here
As to the "read-only" mode, the widget can be only in edit mode (readonly is not supported). The only solution that I can suggest is to place a overlay element on top of it, thus preventing the user to click.
As a side note, the DatePicker widget
supports "readonly" mode, but it is an input editor different than the Calendar itself.