How can I show the heading number after the heading itself?

Questions
2

You can get the heading number from the built-in counter. The counter requires context to evaluate/display, and the block is used to get the default behavior of a heading.

#set heading(numbering: "1.1")
#show heading.where(level: 2): it => context block(
  it.body + [ ] + counter(heading).display()
)

= A Section
== A Subsection
== Another Subsection