How does push notification work really?

I went through an ebook today and the idea of push notification ads for CPA offers got my attention.

Now in the ebook. The writer made mention of some platforms to run PN ads like propellerads, richpush, popads etc.

Then he says, one can use it to drive traffic to your site and also grow a PN list sort of. And i can send messages to that PN list to drive traffic to other sites like CPA or a second site where I can have ads as an advertiser.

I am just a bit confused as to how all this tie together. He did not go into detail. Can someone help me out?

Here are my questions:

1. When I order traffic from say popads..is the traffic automatically added to my PN list? Or its just traffic to my landing page.
2. Basically, he calls it arbitrage where I can buy from one platform and sell on another...i am assuming this means sending traffic to another site I own that displays ads from another PN site.
3. What platforms are best to use for this method

Thanks guys