Rest Sensor Strip JSON

Is it possible to remove part of a JSON data string?
I’m using the value_template to extract the appropriate data but it contains the unit on the end which i wish to remove so i can use it with the statistics sensor for averages.

Would it also be possible to include a sensor state as a variable in a HTTP GET resource address?

You can test such things in Dev Tools/Templates:

{% set str = '23 °C' %}
{{ str[:-3] }}

Don’t know about the second question.