LOL I’ve been playing this about a week on PS4 and I’m struggling a bit (Perfectly normal in a new game, I know) but I’m wondering how the Co-Op system works.
For instance, on Borderlands I could hop onto a friend’s game and help them level up because I was ranked higher and they were stuck on a particular mission. Is that how it works in this game or is it set up fundamentally different?
Thanks in advance.
You can hop in a friend’s game but it will be like if you begin to play on a server for the first time (have to create a character, etc.) 
First & foremost: Thanks for the answers, both of you. I have 2 more questions, one unrelated.
If their character stays in-game, is it simply idle or does it assist me while they’re not there?
Secondly, I’m considering buying a DLC and I noticed that it contained armor. Do I have to craft that or is it automatically added to my inventory, ready to be equipped? If I have to craft it, it’s basically useless at such an early stage of the game.
@Genesis_3009 most players while not in game are idle or “sleeping” (bodies laying down exactly where they were when they got off)
The armor for the DLC are craftable armor but they are equivalent to iron weapons and armor, with an end game lvl 60 version as well.
I found them to be a nice replacement for the usual armor early in game and for looks after. Plus tier 3 building peices are much nicer looking.
Long as you have a forge, armour’s bench, and a blacksmith’s bench you can make them as they are a feat you automatically know.