Did you login to publish as admin? Use localhost:4503/login, login using admin creds and then open crxde

If you want to customize or extend the OOTB sitemap generator, refer this - https://experienceleague.adobe.com/en/docs/experience-manager-cloud-service/content/overview/seo-and-url-management#building-an-xml-sitemap-on-aem 

If you want to add a node, use a dialog listener, call a servlet which will perform jcr operations. I am not sure whether this will work in AEM Cloud.Some dialog listener reference which calls servlet - https://kiransg.com/tag/dialog-level-listener/

Do you mean that component should be added as a child component? Why do you want to change the dialog nodes? It is not recommended to change dialog nodes dynamically. Content change is fine.

1. How secure the servlet is - It depends on what access the node which has that resoucetype, has.2. Request has what user permissions - The permissions of the user who is accessing that node, which triggered this servlet.

Is the requirement to show or hide a field based on dropdown selection?

You can identify the live copies based on the following -1. The live copy will have some properties under jcr:content like cq:lastRolledout and cq:lastRolledoutBy. These properties will exist under jcr:content/metadata also.2. There will be a child node under jcr:content called cq:LiveSyncConfig. Yo...

This might happen if the metadata schema is deployed through code and it is overwriting the existing metadata schema in AEM Assets. Did this issue happen after code deployment? If yes, then the above might be the case.

The Asset Java APIs are deprecated - https://experienceleague.adobe.com/en/docs/experience-manager-cloud-service/content/assets/admin/developer-reference-material-apis#deprecated-asset-upload-apiYou will need to use aem-upload method mentioned in the docs here - https://experienceleague.adobe.com/en...

By default all selectors are denied in dispatcher filter, unless specified.If you do not want this selector called "test", deny it in filter. If you do not want selectors for this page, deny selector for this page.