Question : What kind of router to handle multiple external IPs?

I need to handle 2 external IPs with my router, which provides DHCP for 3 servers.  (Really, 1 IP is for all 3, and the other IP is for 1 of the 3, so the "multiple external IP" really only applies to one of the servers on the network).

Do I need a router with dual WAN ports -- or is the capability to handle multiple external IPs different than the quantity of WAN ports in a router?

Answer : What kind of router to handle multiple external IPs?

Handling multiple external IP's is a function of the router and has nothing to do with physical ports, unless the 2 external IP's are from 2 different service providers, on 2 different IP subnets..
Any Cisco product will handle the job for you quite handily.
What you're looking for is something that can handle both 1-1 NAT and simultaneously use PAT overload for the other two.
It also depends on what your WAN link is. Ethernet? Check out Linksys RV042 or Cisco ASA5505