Understanding REST, json parsing and templates

I admit I’m having an hard time trying to use templates…
I’m trying to display in a card the JSON from the bus stop arrivals data.
The url is something like “http://www.mysite.com/data.php?stop=$number”, where $number is the code for the bus stop.

The json produced by the query is something like this:


I created a test sensor with a fixed bus stop:

- platform: rest
  name: Arrivals
  scan_interval: '00:30'
  resource: 'http://www.mysite.com/data.php?stop=755'
  value_template: '{{ value_json.line }}'
    - line
    - hour
    - realtime

After I have used a sensor card in lovelace to display the data:

type: sensor
entity: sensor.arrivals

First question: I don’t see any data but a graph bar in the sensor card, I need to click the bar to see the data, how can I display directly the “line”, “hour” and “realtime” values?
Second question: with my “template” I only see the first set of values, but the JSON contains more: how can I iterate through all the data and display all values?
Third question: is there any way to interactively change the $number value which gets passed to the url to generate the JSON?