Brew works by downloading locally (good in a template based qube), and
symlinking in to /usr/local - again good because those directories are
stored under /rw and are specific to each qube. You’ll want to increase
Private storage.
That’s a very good fit for Qubes.
Again, a good option.
Which should you go for?
A template based qube is easy to update, simple to clone, and takes fewer
resources than a standalone. I almost always go this route.
Where we might differ is that I would use a clone of the Debian
template, and install packages there - this allows me to spin up
numerous qubes as needed to try out different approaches. This might not
be something of interest to you.
I never presume to speak for the Qubes team.
When I comment in the Forum or in the mailing lists I speak for myself.