Frappe webform customisation

I have couple of questions regarding webform.

Does fetch from works in webform?

How to trigger a function on field value change child table in webform?

Record id is showing in link fields instead of title in webform where as in desk its working fine. How to fix it?

Check Customising Web Form Documentation
https://frappeframework.com/docs/user/en/guides/portal-development/web-forms

One Additional Event of Web form which is not in documentation