To summarize for anyone that might be new to multiple static IP addresses on cable based systems.

My local Comcast provided the gateway (CG3000DCR). 
After a phone call to business tech support, they (Comcast) removed firewall, port forwarding, DHCP server and few other things, which put the gateway into bridge mode (or as close to it as you can get).
I could have also done it myself if I knew which settings to disable.

With Comcast, there is no username, no password, no PPPoE, that needs to be setup in the router, which makes things simple.

Tell the router, in my case Mikrotik RB750GL, which one of the 5 (or 100) IP addresses you want to use, configure about 10 other things (covered in the video) and you're ready to go.
If I wanted another network setup, I would follow same process until I ran out of addresses. 

As someone pointed out, if the gateway doesn't have enough ports (mine has 4), than simple, unmanaged network switch between gateway and n-routers will do the trick.