1) You'll find this under "Security & SD-WAN" -> Appliance Status -> Uplink
There you can change the IP from DHCP to Static.
NAT will be automatically done for all outgoing traffic.
2) This is done under "Security & SD-WAN" -> Addressing & VLANs
There you can decide if you want to have multiple VLANs, configure your internal IPs and also set static routes if you have VLANs on the internal switch.