It sounds like you are describing something along the lines of Experience Fragment building blocks, see here:Adobe Experience Manager Help | Using AEM Experience Fragments

Why have "/" configured as the path for all of them.  To avoid having to do some special handling you could have each handler configured with "Path" pointing to the site (e.g. for the www.aaa.com handler the Path field would be /content/aaa).  Then when the user goes to the site (they should be visi...

Uninstalling SPs and CFPs is unsupported as Kunwar stated.  However, if you must revert it and do not have a backup.  Then try this:1. Backup your AEM instance2. Package up the /libs folder from another working environment and installing it to the post-CFP environment.  Note that you must also make ...

Please see this article:Login session refresh not working in AEM 6.x As a workaround, to add some expiration functionality, you could implement a custom javax.servlet.Filter to handle session refresh and expiration:a. Download and modify this sample filter code to meet your needs:https://github.com/...

See here to download the latest fix pack for AEM 6.3: Release Notes: AEM 6.3 Cumulative Fix Pack

This is a known product issue CQ-4230772 which is fixed in 6.3.2.1 (AEM 6.3 SP2 CFP1) and AEM 6.4.

It would make sense to implement oauth for this.  See this presentation for details:OAuth Server functionality in AEM - Embrace Federation and unleash your REST APIs!

Try installing a newer version of the vlt rcp bundle to the source and destination instance and try again.  See here for the newest bunde:Central Repository: org/apache/jackrabbit/vault/org.apache.jackrabbit.vault.rcp

Are you referring to this? Redirect Map Manager If so then that is part of the ACS Commons open source project and you would need to download and install ACS Commons to your AEM instances before you could use it.  See here Adobe AEM Commons.Here are some instructions that might help you in setting i...

Since you found that a system user permission was missing you might want to repair all the system user permissions.  Somebody most likely installed a package containing ACLs which overwrote the out-of-the-box ones.  There are probably other users that might be missing their permissions.  See this ar...