If we have 2 author instances in cluster with MongoDB, where are the Web Console Configuration saved?I mean, changing any bundle configuration from: /system/console/configMgr. They are saved in MongoDB or filesystem? Configuration are shared between the 2 Author instances or stored separetely and so...

The bundle not starting is a custom bundle?If so, check if you are declaring the correct uber-jar version dependency for your instance. 

How are you retrieving the json object? Maybe the request is blocked by the dispatcher

Have a look at Assets HTTP API

Have a look at Assets HTTP API

If you are retrieving the json clientside you need to sort it by javascript.If you are retrieving serverside, you need to sort your list before listing with sightly markup (with JS or Java API you are using)

You can have a look also to Contextual Pathfield Browser of ACS AEM Commons