Need Help Before Purchasing

[Batman1955]

Good Day:
I am considering purchasing either and SG-1100 or SG-2100 for my home network. I have tried to find some examples or documentation that would cover a conceptional and technical overview of how to integrate the firewall into my existing network. My current network is as follows:

1. ISP Spectrum
2. Spectrum Modem via cat5 ethernet cable from wire closet to Netgear R6900P router.
3. Router has IP address assigned from ISP.
4. Router has TWO private IP address spaces configured for home and guest user networks.
5. VPN server connected via cat5 ethernet cable to router.
6. All other systems (23) connected wirelessly to the router.
   Q1. Which one of the two firewalls would you recommend?
   Q2. Given my current configuration and the research I have done so far, I think I would just be able to take the cat5 cable from the routers WAN port and plug it into the WAN port on the firewall and then take a cat5 cable plug it in to one of the lan ports on the firewall and then plug it into the WAN port on the router. Is that correct? Will this allow the ISP address to be assigned to the router?