Drupal 8.x

I have the module Message installed on a Drupal 8 site. I want to display the information of the author of the message but I can't figure out how to do it.

How can I display :

- the url of the account of the author.
- the name of the author.
- the picture of the author.

The following codes do not work :

    {{ message.author_name.url }}
    {{ author_name.value }}
    {{ author_picture }}

This code doesn't work :

I have an integer field that I am trying to get my template to display differently only if it contains "0". Though I cannot get it to output correctly.

{% if content.field_caves__max_level.0 != 0 %}
  {{ content.field_caves__max_level.0 }} Max
{% endif %}

I've tried numerous other combinations including

What I want to do seems simple on the surface, but I haven't found a good way to do it yet. What I want to do is to limit what users can gain access to by their system role. We are using SimpleSAML Authentication module for authentication and automatic role mapping, and content moderation to allow content workflows.

I have a View that displays summaries of concert events on one page. One field of each event is a Vendini button, so people can buy a ticket. This all used to work, but now, all the Vendini buttons are shown in the first event, instead of being placed in each individual event. See https://orcma.org/chamber-series

My View settings are at 

https://www.dropbox.com/s/uftsa4yqydz8js0/Chamber1.png?dl=0

I am trying to upgrade the version of drupal/acquia_connector running on my site. The trouble is, when I try to upgrade the module with a composer update, composer throws an error and refuses to do the update. I'm hoping someone could offer some help with either:

getting the upgrade itself to complete, or
at least understanding the composer error message in hopes of further diagnosis.
Here are some details.

The site is currently running:

I want to create an image style that shows a blurred image as background of the sharp image. Is it at all possible to use the source image twice in an image style, first as blurred background and a second as normal smaller forground image?

I tried it with a view with the two image versions, one as background of the other using the bg_image_formatter but it has an unfixed bug that makes it useless for my purposes.