As Ravi points out - you should include Clientlibs the correct way - using a script tag does not address best practice.

You can use an AEM workflow and create a custom step that reads the payload that gets the file names. This will get you started: Adobe Experience Manager Help | Replicating Adobe Experience Manager Content using the Replication API

Joerg is correct - you should not be using a Servlet like this.

I strongly recommend that you work through this Weekend tutorial to learn the best AEM development practices. You are asking questions covered here: Getting Started with AEM Sites - WKND Tutorial

Are you trying to read OSGI config values? 

I am very glad it worked for you. This the entire purpose of these working code examples.

You could easily create a custom form action that sends submitted data to an OSGi service. Then you can write Java Database logic to persist the data into a relational database.

You should try to use the Responsive grid to define a layout. It will be smoother to move CARD components within it. i will try this and post back.

I do not think that error is related. Try the article step by step. It does work - as you can see the video at the end.

Follow this exact article - it works nicelyAdobe Experience Manager Help | Querying Adobe Experience Manager 6.4 JCR data using the QueryBuilder API