Thanks for the reply, so it will be Active-Warm Spare configuration. Can you advise how it should be configured for WAN links? I believe every ISP should provide me 3 IP address and then I need to configure it with VRRP?
VRRP is automatic with the MXs. Put one IP on the primary MX, then another on the secondary and then a third on the virtual IP. Once that is set, you can either make one WAN connection the primary and the other a failover or you can load balance by IP/Network. See here for more detail.