Managing different profiles in the Thinkpad Access Connection utility is pretty easy. So just setup a profile called Home with the following:

Fixed IP address: 192.168.1.50
The first two terms should be same as your router. Normally DHCP address assignments start at xxx.xxx.1.100 or xxx.xxx.0.100 and runs 50 addresses to e.g. 192.168.1.149. So setting an address outside of this range is safe.

DNS addresses: 192.168.1.1
I agree with abm12.
The Gatway router should have DNS forwarding function. So you can just point to your Gateway router address and not to the actual DNC server the carrier gives you. Sometimes this can be 192.168.0.1

In my network, the DNS addresses are actually held by the DSL modem. So I can point to the GW router address or DSL modem address in each client DNS address field entries.

Gateway and Subnet Mask: Same as your router settings.

WAN address:
Because my DSL modem can hold the PPPoE log on function, there is no need for my router to do so. The WAN port (internet) is set to Obtain an IP automatically.

Additionally, in my network, all network devices such as routers, wireless access points are assigned in the range 192.168.1.1-10, fixed client IP addresses in the range 192.168.50-99, DHCP addresses in the range 192.168.1.100-149, printers 192.168.1.200-220, and NAS storage devices 192.168.1.250-254. Each device has its IP address marked.

In my network, the functional split amongst the different devices are as following:

DSL modem: PPPoE and DNS address holder
Main router: DHCP server, GW address, VoIP phone function, top level switch
WiFi access point: WPS-PSK authentication
8 port Gigabit switch: main network switching

The WiFi AP and GB switch actually are high thermal devices so removing these functions from the main router had reduced network crashed to negligible level in my network.

Network devices should have web access administrative function turned off and WiFi access points with authentication turned on for security.

First use of ethernet was actually when "cheaper net" thin wire ethernet got started in the mid-eighties. The thin coax cables were much cheaper than the thick coax and taps but was very unreliable and a single connector can bring down the entire network. The star topology in hubs and switches were a god send.