Need help understanding comps, was invited to a first round interview at Wells Fargo Securities

Hey guys,

So thanks to the help of this community I was able to land a first round interview at Wells Fargo Securities. My contact person at the firm told me to be prepared to answer the following questions for the summer analyst phone interview:

"Know the operating model--have a high level understanding"

"Walk through how the three financial statements are connected"

"Understand comps, leverage always backwards, transactions always look backwards, precedent looks forwards"

My question here is specifically centered on the comps question, but if someone can explain the operating model one as well as the financial statements connection that'd be much appreciated as well.

TL;DR Can someone explain to me what this guy means by the first statement and the third?

Thanks guys.

Also, if anyone needs help w/ how to cold-email and get a response feel free to PM me--I've done this the past few weeks with an immense amount of success.