Postgres Replication on a different network interface

Hi Experts,

I had done replication earlier in EDB 9.6 version using simple WAl
replication.

My master server is listening on localhost.

Example:
listen_addresses = 'localhost,158.245.240.209'

I have another additional IP configured on my both master and slave
servers which is a dedicated network for my replication traffic example,

Primary : 172.176.43.112 , Salve: 172.198.47.101 ,

Question:

Can I configure this Ip only for replication ?

My understanding:

postgresql.conf:

listen_addresses = 'localhost, < what all ips we should configure here>'
/// Do I need to add these replication traffic ip address here?? Please
help

On Master
wal_level = logical or Hot_Standby

max_wal_senders = 4

max_replication_slots = 4

On Replica
In addition to the above, the following need to be configured on the
replica:

hot_standby = on

hot_standby_feedback = on

pg_hba.conf:
host replication repuser 172.198.47.101 /32 md5

Salve:

standby_mode = 'on'

primary_conninfo = 'host=172.198.47.101 port=5432 user=foo
password=foopass'

restore_command = 'cp /path/to/archive/%f %p'

archive_cleanup_command = 'pg_archivecleanup /path/to/archive %r'

One more question?

If I have to replicate the replication traffic from master to 2 different
sites.

Site1 ( Production) Active: One Primary (read write) M1 , 2nd one is Slave
(read only) S1

Site2(Disaster) Passive : One Primary (read write) M2 2nd one is Slave
(read only) S2

Note: I have already configured replication within the site1 , where slave
get the wal file using wal replication.
Question?
Do I need to add another server as slave the Site 2 and replicate from the
Production Primary ? what is the best practise. ?

The sync I have plan is : M1->S1 & M2 , and then M2->S2 // please advise.

Regards,
Sanjib