pf/opnsense question

I'm gonna virtualize one of these sooner or later to get some networking hands-on experience for myself. While I don't plan to throw my current router in the trash day 1, how (not?) safe is it to switch over to using it as your router in the sense of making sure things like basic firewall protections and whatnot are up? Is it set and forget and you'd have to turn things off/create exceptions to create huge vulnerabilities, like anything else? Or do you have to build it all from the ground up and know what you're doing entirely?

Also, If down the line I wanted to ditch a router entirely, I'd still want wifi. Is that something where I just buy the cheapest router from amazon and have it only serve wifi, or is there some kind of way I can slap a wifi dongle into a usb port somewhere and have it transmit instead of receive?

Also feel free to have an argument about if I should start with pfsense or opnsense. Leaning toward opnsense since things I've read have implied it's a little easier to set up and start with, and they're similar enough I can always hop to the other.