PvP / Invasion (Dark Souls 3)

Guys. I'm new to DS. Now in 3 parts I have level 67. I would like to know.

Who can I invade? How it works? That is, for example, near a fire, I start a search for an enemy, and who will it tell me, what level will I meet on my way?

Who can invade me, also, any level?

I am a coveant who comes to the rescue, but so far in 4-5 hours of playing, I have not received requests for help or anything like that. How does it all work? Tell who is not lazy

And the question is, who can I summon, for example in front of the boss, what range of levels or what influences the summon of someone?


The question is very interesting for me, like the pvp itself. But the mechanics, how what works, who and where can be summoned, alas, I do not know.

Please help me