Have you gone through the below documentation of integrating Adobe Campaign Classic and Analytics? There are multiple options and you can choose and implement based on your requirements. Analytics to Campaign v6 Implementation Guide

Have you gone through the following documentation - https://docs.campaign.adobe.com/doc/AC/en/DLV_Tracking_messages_How_to_configure_tracked_links.html ?

Have you gone through the Amazon AWS command line reference - Using High-Level (s3) Commands with the AWS CLI - AWS Command Line Interface  I guess you can write a shell script calling these commands and create a cron to upload the files automatically.

You can definitely  create AEM pages programmatically by calling backend JCR and AEM APIs. The AEM repository allows you to programmatically create new nodes and perform other CRUD operations. The content which you are migrating can be loaded into AEM after you know how that content is going to be r...

I think the Adobe customer care will provision an S3 account for you if not already done. Some details are available here on this page - Beta Environment See - Provision Amazon S3 Buckets

Did you check the advance process handler checkbox in the process step configuration?

I don't think so as FTP isn't supported any more. You can only use S3 bucket to onboard offline data. - FTP Name and File Size Requirements for Inbound Data Files

Check this documentation and example - Apache Sling :: Scheduler Service (commons scheduler) 

If you are looking to setup open source Asset Share Commons then you can download and install the packages from here - Releases · Adobe-Marketing-Cloud/asset-share-commons · GitHub  Minimum version it is supported on is - AEM 6.3 SP1

You can register your servlet to a more generic resource type and then use OptingServlet interface to accept requests which meets your dynamic qualification criteria. For more details see this documentation - OptingServlet (Apache Sling 7 API)  - Your logic can be defined in accepts method. Example ...