Hi. How would I configure gnus to reply to "From:" and also follow-up to
"Newsgroups:" at the same time?

Default behavior is just follow-up to "Newsgroups:", with or without
quoting:

  F - gnus-summary-followup-with-original
  f - gnus-summary-followup

Also, is there a particular etiquette w.r.t. this?
Thanks.

-timotheus