How can we make the summary field auto expand on load?
You could do it with the Summary Options module.

This module provides site builders with additional options for the
'summary' field when using &quot;Text Area with a Summary&quot; widget.
Often, a summary or teaser field is used when displaying content in
views. Drupal already has built in support for a summary field,
however there is not much control of whether or not it is display, or
required.