Catching up with the City- who are these people?

I have officially watched, what, five episodes?  I admit I have a short attention span and am usually doing a few things while watching TV but I am confused and have a series of questions regarding this series:

-WHO is Erin?? I keep waiting for the explanation of how they met or anything connecting back to the idea that they have known each other longer than the show. Is this another Audrina/Heidi situation or are Whit and Erin really for real friends. 

-Who is the guy in the beanie cap and fur collared coat? Who is the girl from the airport? What's going on? I need some help, ladies. 

-What percentage of the new apartment is MTV paying for? Any chance it is less than 100%?

-Does Olivia have any friends aside from her cousin? (Olivia told him NO GIRLS over- is this really an issue for Nevan? BUT I am loving his short new york answer to Olivia making fun of his shoes- "they're super comf!")

I need help answering these pressing questions because at this point I am not getting into the drama because I just don't understand. Are there Cliff's Notes?  I will be anxiously awaiting answers in the comments...

I am thinking they need to relate every person whose name pops up on screen to Whitney- "Whiny airport girl- Whitney's sometimes boyfriend's college roommate's brother's best friend's girlfriend"or whatevs. Work on it MTV.  Make it easy for me- I don't watch the show to increase my brain capacity.  That's what video games are for.