It's not confirmed but it's assumed to have a slightly lower chance of getting a Shiny than the Masuda Method.
But I can hatch say 5 Eggs in 10 minutes with a Pokemon that has Flame Belly in my party or I can encounter roughly 30 - 40 Pokemon in 10 minutes in the Safari, Just make sure to bring a Honedge in your party to make encounters more likely to happen.
So yes, you're getting more faster chances with Friend Safari's
I'd help you, but keeping track of it may take a while. I'll get back to you later with my data.
I just traded a Torchic that got from wonder trade for Regigigas
OK, your clearly getting hacked pokemon for your legit ones. There's no way somebody would trade a Regigigas for a Torchic under normal circumstances(especially with how hard it is to actually get Regigigas)
Or, as is commonly known, cloned clones.
Either way, he's basically getting scammed.
Believe me, It can take ages, My search for a Shiny Espurr has been going on for nearly two days now.My attempts to catch shiny pokekon have failed -_-"