The name comes Kotlin, the language we run on, and Jot, as in to write something quickly.
This language uses logic to try to shorten kotlin code.
To avoid falling foul of the custom language for a challenge rule we avoid making builtins for specific challenges.
According to this, yes.
There are multiple ways to run the Jotlin runtime
docker run --rm -ti -v "${PWD}":/dir:ro jrtapsell/jotlin run examples/142243/metadata.json
java -jar jotlin.jar run examples/142243/metadata.json
A list of builtins is available here.