As for the matchmaking, your soul memory and soul level are matched to similar people.

Noiceeeee lol tha ks, that's beneficial to know

Forgot to mention that the Belfry areas (one is near the Lost Bastille and another is connected to Iron Keep) are other pvp hotspots linked to a covenant Co-OP is easy, just drop your sign practically anywhere. Outside more difficult bosses works best, like The Pursuer, Mirror Knight, Fume Knight, Sinh, Freja, Old Iron King, Lost Sinner, etc