Trying to understand manual router set up and more

[#1]

Are these details the ones needed for PN? 

Some people do not use DHCP for allocation of IP addresses for connected items, but numbers, 10.x.x.x.

What are the pros and cons of such fixed IPs; what situations would make them worthwhile in a domestic situation?

[#2]

I cannot see anything in the settings that is specific to Plusnet.  The Gateway and DNS boxes seem to have comments rather than actual values.  The router IP address and subnet prefix length can by anything you want.

[#3]

The insertions are what I believe needs to be there, were I to set up a router for a Plusnet connection manually. But never mind.