https://www.facebook.com/business to schedule an appointment with an FB expert to help setup advertising campaigns and setup your like pixel, for FREE.
Pixel and pretty mega and allow you to analyse all the traffic hitting your website, so you can create custom audiences from the people that hit the site and extend that audience using people that are similar on FB, so its very powerful. I found some strange stuff on the adverts without using pixel, just using the audience creation I've had better results just going board than I did going super narrow via that audience choice. I hope to get better results using the pixel once i get it working right!! See Pixel helper post previously..
I guess you also need to take into account Facebook want you to use their systems and aren't necessarily bothered about other methods that may be better. That said I am very happy to use as much of their help to learn more for free!!