Configuring Always On with mixed public/private network

Hi all,

I need to setup AG including 4 nodes:

Node1: Primary

Node2: Secondary(sync commit)

Node3: Secondary(ASYNC commit)

Node4: Secondary(ASYNC commit)

There can be crossover link only between Node1 and Node2. According to articles, for this setup I need to have additional NIC on Node1 and Node2 to support private network for syncronization.

My question:

1) Do I need to configure more than one endpoint for Node1 and Node2? I ask because Node3 and Node4 cannot communiate directly(private) with Node1

2) If I intend to have Node3 sync via private network, I have to add third NIC to Node1 and second NIC for Node3?

I hope my explanation was good ^_^

Many thanks in advance

Leila