Program files mainly are in /usr. If you want the whole file hierarchy
standard, here it is:
http://refspecs.linuxfoundation.org/FHS_3.0/fhs/index.html
I am not very knowledgeable when it comes to networking. Cannot DNS server be
automatically discovered (and be those of your ISP)? If so, I believe there
is no default.
Abrowser and Icecat are Firefox derivatives. Firefox add-ons (such as Random
Agent Spoofer that I mention and works against fingerprinting) work with both
Abrowser and Icecat. Abrowser's add-on repository exclusively contains free
software (no need to check by yourself): https://trisquel.info/browser/addons
