Jobs Listing Schema Markup for SEO



I'm curious as to how to edit the mapping of schema metadata and information within job postings. Most specifically, description, skills, qualifications, and responsibilities are all conflated within the way that job postings are laid out in our ICIMS tool. I'm hopeful that I can set up each field in the ICIMS job postings wizard so that it guides the user to enter data appropriate to the property within the jobPosting schema. The users at my organization like having their postings broken down with custom headings, but I want to make sure I can also map their custom headings to the appropriate jobPosting metadata.

Here's an example of what I'm talking about:
https://validator.schema.org/#url=https%3A%2F%2Fcareers.thearcoway.com%2Fproject-managers%2Fjobs%2F7582%3Flang%3Den-us

You'll notice that whole sections of the posting are shoved into the "description" section because there's no better way to say what info they contain.

My other concern is that some items, when not filled out, lead to the output "0", and some lead to "null", or "unavailable," or similar. Is there any pattern as to what null value is used, and can we preempt it?