Subdomain delegation is required. Also, it's not recommended to use a parent or corporate domain as it could impact the delivery of email from your organization to ISPs as it may lead to an increased risk of recipients marking emails as spam, especially if the frequency is high or the content is not...

You can change this using "Compute the label during delivery preparation" from the delivery properties provided the Aggregation period is "No aggregation" - In effect, you will see multiple delivery executions being created.  

You can use the segment in the condition as well (using inSegment() function) and if you are looking to directly access the message feedback event attributes in the condition in a journey that starts with a read audience, or an audience qualification or a business event activity - that's not support...

you can create a batch segment leveraging the attributes from message feedback event schema and accordingly suppress it, within the journey.This schema / dataset contains the message delivery logs.

No, it's only profile attributes at the moment.

Journey status is currently not available in the system datasets

Throttling rules are configured on production sandboxes only, for a specific endpoint but global to all journeys across all sandboxes. You can have only one throttling configuration per organization. Capping rules are configured at sandbox level, for a specific endpoint (the URL called) but global t...

Journeys that are visible in journey orchestration solution view are visible under journey optimizer.You will be able to pass the payload from the source journey to the destination journey and accordingly configure your criteria in the downstream journey but you won't be able to jump on a specific c...

Kindly refer to the collection management functions detailed in this documentation https://experienceleague.adobe.com/docs/journey-optimizer/using/orchestrate-journeys/building-advanced-conditions-journeys/syntax/collection-management-functions.html?lang=en

You can query the message feedback dataset to find more insights on the error https://experienceleague.adobe.com/docs/journey-optimizer/using/reporting/reports/query-examples.html?lang=en  Similarly, query the step events to find out the exact profile entrances / exits by applying the relevant date ...