What are the most important tasks for setting up a new PC running Windows?

#1 -- Firewall (included and activated with Windows 10)

#2 -- Anti-virus (included and activated with Windows 10); skip the all-in-one suites.

#3 -- Windows Update (do NOT disable this on any PCs)

#4 -- Backups (ya snooze, ya lose -- sooner or later); focus on your data files first; also consider online automated backup services such for complete protection (fire/theft/PC crash)

#5 -- Networking: peer-to-peer is easiest to setup and manage (no IT assistance or maintenance required); single workgroup control; create no more than two user accounts per PC (users are for business offices with cubicles, not shared PCs in a retail environment where employees move from station to station)

As far as the browser debate goes -- we side with MS Edge and not because of the Microsoft logo.