Two things can create issue:1. your components configs- Can you share the editconfig node2. component specific CSS?Can you share any screenshot?

You should be seeing line no where NPE is occuring, can you check?Also is that the complete code?Make sure you bundle is resolved in felix

code will not compile if that's the case

No additional packages or installations are required on AEM 6.4 and later.Adobe Experience Manager Help | Getting Started with AEM Content Services - Part 1 - AEM Content Services Set up Which version of AEM u are using?

AFAIK, Touch UI fieldDescription does not support this.

Yes, they can't be deleted from AEMit's a known issue

Those will go into core

model is the selector used by page model sling exporter.When you have custom implementation of component sling exporter, you have  to give the path to component in repository and then use model.json on it

You can't use JSP method in HTL file.But you can use JavaScript use API, any specific issue with it?

It does not follow the name pattern, you can change file name to cq-publish-p4503.jar and delete crx-quickstart folderthen start again