Privacy

disadvantage to installing librewolf (or something similar) as my primary browser instead of default firefox?

LibreWolf comes with more anti-features disabled. If you use LibreWolf's default settings, you'll discover which websites are built by assholes. Many answers will not surprise you, but a few might.

LibreWolf can be configured either site-by-site or globally, to allow whatever anti-features you are comfortable with. The disadvantage jin LibreWolf is needing to change those settings. I guess the advantage is knowing and having ou a choice in his much you are tracked.

What I particularly like about LibreWolf is it ships without stupid crap like Google search or Pocket. Since I always remove both, LibreWolf saves me some time, overall.

Edit: When picking the "everything will probably work" setting in LibreWolf, I find that everything works. The exceptions I encounter are rare.

As a programmer, I investigate those rare exceptions. My judgement is that the website owners are total assholes who felt they needed to collect every single tracking mechanism known to mankind into one site, while also just being bad at building a website.

I'm sensitive to assholery, so maybe I don't spend as much time as average on sites written by assholes. So my "rare" might not match everyone's experience.

What are some of your goals, motivations, restrictions, and threat model?

Hard to give great advice beyond generalities without knowing more.

I would encourage to check out Konform Browser! (am dev) It's significantly more relevant for privacy than Firefox without compromising on functionality.

In any case a benefit of QubesOS is that you can easily use several in different AppVMs so you can mix and match. Regardless of whatever else you use I guess you will always have Tor Browser on the side to, for example. Having something chromium-based like Helium or ungoogled-chromium on hand for when you need it makes sense too.

If I do want to do this, is there a recommended method beyond “install it as normal in the template”? I notice that when creating a new qube, there is a menu for additional applications; how exactly does that work?

In very short: That's basically it. You can generall install applications two ways: system-wide in template (e.g. with your distro package manager), or under /rw/ (usually more specifically under /usr/local or /home/user). The "menu for additional applications" is about what .desktop applications you will have access to in QubesOS. That functionality should handle both cases as long as in supported path. There may be specific cases when you want to install apps in AppVM but template is usually recommended.

If you would like to explore setting things up using configuration management rather than doing it manually, qusal is good inspiration.

do you trust mozilla?